The last two constraints

Hey there, I got confused on the last two constraints, in which the video explained that Q & T and also S & R cannot be together in the last talk as they accompany each other in their "first talk". However, isn't it possible that (for example) Q accompanies T in an earlier talk and also accompanies T in the last talk (same thing with S & R). I just don't get how they cannot be together in the leadership talk. Thank you in advance!