Why everyone so confused?

I think it's kind of okay; it's either good or bad. But I was really confused about the purpose of their "practice." I understand that the ML is a popular actor, but it's weird that the Uke wouldn't question why they need to do a " sex gay" scene. Like, will the MC be part of BL drama or something . And I've read some comments that their sex scene felt awkward or like they don't have chemistry (?)