How anyone could see her behavior as somehow being "better" just because there is no age difference between her and Miyako is honestly beyond me.
Tbh, Matsumoto had her sweet moments with Miyako and the two have a lot in common. Nobody said her behavior is better. It's just their liking. I mean, in the end peoples like the ship they want. As long as you don't shame the others ships, it's all good.