Not sure how anyone is surprised about his refusal to act. He clearly has no interest in it unless it’s something that can help the sisters. I can totally see an acting arc where he supports one of them as an extra or something and gets noticed, but he definitely has not wanted to be an actor since he was a kid (and that was only so he could try and connect with his mom)
this has been 100+ chapters about yuu supporting them and breaking away from the idea that that’s “less” then being a big famous person. remember his ultimate goal is to become a family with them.
It has already been established that Yuu can't act for shit unless he is around the sisters and not even aware of what he is doing, so acting would have been a shit choice of carreer for him. Also he would still be under his mother's shadow.
Clearly working in a host club is better suited for his talents.
I don't even think it's acting. He's had the face of a world class actor the entire time, he just doesn't know how to use it. When he pops off like that it's because it's genuine
I mean readers being disappointed should've known that Yuu would refuse the offer right away. He didn't really have an interest in acting and was just doing it just because he was the son of a great actress in the past.
He's more in line being with his "family" that he always wanted and what his mother wanted.