You could also argue against that. YNGMYM and Sun King are two complete and seperate songs, must like all the preceeding album. Just because there's no gap between Sun King and Mr. Mustard doesn't mean it's part of a medley. It's just good album production. I mean, it's pretty stupid to even argue about this one way or another, because the whole second half of the album is only how it is because the band hated each other at this point and couldn't really finish all these songs they started. Thank God for George Martin.
But the reprise in Carry That Weight doesn't automatically include YNGMYM in the medley. Are we going to argue that the SGT Pepper reprise constitutes a full album cycle, so it's all one grand concept suite? I mean, not quite the same case, but you get my point. I'm just saying, if you added a one-second gap between YNGMYM, Sun King, and Mr. Mustard, the album would still sound perfect. If you did that with the real "medley tracks" it would sound horrible. That's because YNGMYM and Sun King aren't in the "medley".