Because more than 2 of them would need to come back to Earth.

I thought about this overnight and isn’t the real problem that nobody is saying is that NASA never wants less than 1 re-entry module on even an empty ISS, so that if god forbid they had to evacuate everyone for any reason other than a dead station, that the next crew has two ways to get home?

So even though everyone fits in the existing modules there is no spare if they let these two go home.

Yes exactly.