I felt the same for a moment but the end kind of made me realize they were all participating anyway when one of the boys eagerly took on the task of helping coordinate more visitors.
They all got to see the visitors, they all got to enjoy the decorations, and the only difference was that the girls wore flowers in their hair.

We get to keep ours as a player for glam reasons but realistically these will wilt in a few days, it's not like they got a new bike while the boys got nothing. If one of the boys expressed an interest in having flowers in his hair and didn't get any then I'd have some feelings about it but otherwise this didn't feel unfair or off to me.