Although it appears by and large that the Tyler shouldn't be an EA if conducting business in the MM degree based on current bylaws, it makes one think about it.
Assuming the Tyler is stationed outside the door the whole time, he wouldn't be present in the lodge for anything he shouldn't be. I actually think it'd be a neat way to have an EA get involved early (assuming that all business is conducted in the MM). Yeah, he's gonna be bored just sitting there while the meeting takes place, but a lot of EAs would jump at the chance of being an officer and enjoying the fellowship before and after the meeting.
KY conducts meetings in the MM degree, which means that new brothers often don't interact very much until they reach that degree. I know that is why a lot of lodges are moving to conducing business in the EA. To me, assuming the Tyler stays outside, there wouldn't be an practical reason he'd need to be MM.