Brother Wunsche has some of his wires crossed on this. First of all, the organization created by William H. Koon, II, immediate Past Grand Master of the Grand Encampment of Knights Templar, was officially called "The Grand Priory of the Reformed and Rectified Rite of the U.S.A." Note that the word "Scottish" does not appear in that title. It purported to confer the degrees of the old "Rectified Scottish Rite." Note that the word "Reformed" does not appear in the name of the Rite. The word "Reformed" only appeared in the title of Koon's bogus organization. It is true that the Grand Master's Decision issued in October included the word "Scottish" in reference to Koon's organization, but this was in error.
Secondly, Brother Wunsche stated that Texas Masons are not allowed to receive the degrees of the CBCS. The term "CBCS" is short for "Chevaliers Bienfaisants de la Cite Sainte," or Knights Beneficent of the Holy City, and refers to one of the degrees of the Rectified Scottish Rite. This is confusing, I know. But, the term "CBCS" has, for a long time, been a substitute term for the Rectified Scottish Rite, however incorrect it may be.
Nevertheless, the Grand Master's Decision did not bar Texas Masons from taking the degrees of the Rectified Scottish Rite. It barred them from accepting "an invitation from the Grand Encampment of Knights Templar, or any related Masonic body, to take the three 'Masonic' degrees of the Grand Priory of the Scottish Reformed and Rectified Rite of the United States of America." In other words, it affirmed the position that Koon's "Grand Priory of the U.S.A." was irregular. The Rectified Scottish Rite is not irregular. But, the Grand Priory of the U.S.A. IS irregular.
The original old "Great Priory of America" which received a charter in 1934 is THE regular Great Priory of the Order in this country. Koon's irregular body was a usurper.
In answer to the question, "What makes them (the Grand Priory of the Reformed and Rectified Rite of the U.S.A.) irregular?" the answer is simple but multifaceted. I will ennumerate:
1.) It turns out that Wm. H. Koon II, PGM of the Grand Encampment, did not have a "charter" as he claimed. Rather, all he had was "letters of permission" allowing him and the Grand Encampment to confer the degrees of the Rectified Scottish Rite. So, the "Grand Priory" that he created was self-created and not "chartered" after all.
2.) The letters of permission were issued to Brother Koon by the Great Priory of Occitania, which is itself an irregular Great Priory of the Rectified Scottish Rite. There are only nine regular Great Priories of the Order in the world, located in Switzerland (the Mother Great Priory), America, England, France, Belgium and others, and they are all recognized by the Mother Great Priory in Switzerland, and all nine recognize each other. But, the "Great Priory of Occitania" is not one of them. Undoubtedly, there are other irregular and unrecognized "Great Priories" that confer the degrees of the Rectified Scottish Rite, just as there are irregular grand lodges that also confer the first three degrees.
3.) There is an annual conference of "Great Bodies in Amity" which includes three types of organizations: Knights Templar, Rectified Scottish Rite, and Swedish Rite Grand Lodges. I believe these are all listed in the Triennial proceedings of the Grand Encampment. If you look at that list, you will never see the "Great Priory of Occitania." Nevertheless, in December 2009, in his "Christmas Message" posted on the Grand Encampment website, Brother Koon stated that they had received a charter from "our good friends" at the Great Priory of Occitania. The immediate question that arises is: How did this obscure irregular Great Priory in southern France get to be such 'good friends' with Brother Koon and the Grand Encampment if they are not listed in the most recent Conference of Great Bodies in Amity? The only answer is that they became his good friends when they allegedly gave him a charter. Although, now we know that they did NOT give him a charter, but only "letters of permission."
4.) In early 2010, if you had gone to the website for this Great Priory of Occitania, you would have seen that the Grand Lodge of Occitania shared the website with the higher bodies of the Rectified Scottish Rite in Occitania. Obviously, the Grand Lodge is as irregular, unrecognized and virtually unheard of as the higher bodies of Occitania. An organizational chart that appeared on their website showed that the Grand Lodge and its Grand Master were subordinate to the Provincial Directory and Provincial Master of the Order, an arrangement that would have, by itself, made the Grand Lodge irregular.
5.) In 2010 there was only one regular and recognized Grand Lodge in France, and it was not the "Grand Lodge of Occitania" by a long shot. Therefore, any concordant body of that Grand Lodge would have been equally irregular.
6.) If you had gone to their website in early 2010 (and it may still be there) the Great Priory and Grand Lodge of Occitania had a list of links to other Grand and Great bodies with which they were "in amity" or recognition. Every one of these grand bodies listed (except one) was irregular and unrecognized, beginning with the Grand Orient of France (which admits women and atheists) and its concordant "Independent Great Priory of France," to the Grand Orient of Switzerland, equally as irregular. Of the twelve grand bodies in amity or relation with the Grand Lodge and Great Priory of Occitania, the one grand body that was listed that was not irregular was ... our Grand Encampment of the U.S.A. So, our Grand Encampment of the K.T. is caught in an embarrassing situation - listed alongside eleven irregular bodies, some of which admit atheists.
I could go on, but I think six reasons for irregularity should suffice.