Still don't know what you're speaking of. Remember, not all obligations are the same. Perhaps you could refer me to the page of Duncan's which has the phrase you are thinking of.
However, the phrase you mention is appropriate in the discussion, as that is the point: a determination as been made that another GL is not regularly constituted. That IS in the obligations which most of us share: we do not have masonic intercourse with those who are members of grand lodges/lodges determined not to be regularly constituted.