By cosplay standards that dress is not especially technically challenging, not unless she starts flying around the dance floor and sweating a lot.
Besides, the person who selects that dress has probably been seen topless on several occasions. They are going to be able to handle a wardrobe malfunction if it occurs. This is very unlikely to be the kind of person who thinks that if someone else has seen their naked body they are ruined for life. Some of the relations might be scandalized, but that’s their problem.
