This proves nothing. Frisk can be either. You can go on a date with Papyrus, Alphys (misunderstandingly) goes on a date with you, you can wear a tutu and ballet slippers...
wearing a tutu and ballet slippers can still be done by a male
papyrus knows absolutely nothing about dating
alphys is only doing it because she thinks she is making the human happy
give me some more points and I shall disprove them once more
Remember,
Frisk can be any gender, but most of the community predicts them as female because they're gooners.
UNTIL WE MEET AGAIN-
(THIS IS A JOKE. I DON'T MEAN TO OFFEND ANYBODY. THIS IS JUST A JOKE.)
Okay listen, their gender is up for interpretation and also I don’t get how this means that frisk is a male. This could also just mean that mettaton just wanted to dress up as a girl! In my theater class a lot of boys have tried out for female parts and same go for the opposite gender!