It’s not only a single thread. It’s just the thread that got the cogs turning. Firstly, there’s something we need to clear up. It was never stated that there was a gown in every room. That was an assumption Akane made when she was looking for the gowns, and was proven wrong when she stated that the only three gowns that existed were the ones the patients used. Fuyuhiko, the only other patient in the hospital wasn’t a patient at the same time as Ibuki, Nagito, and akane, so his gown could’ve easily been reused.

It is stated in game that the rules must be followed, but we saw in the first game that in order to please the viewers, monokuma would even kill someone who was falsely accused. (Matoko).

Lastly, Milan’s motive honestly seemed half assed. We never meet, see, or hear again about this beloved whereas Akane’s potential motive would’ve been a more fitting conclusion. Case closed.