Uhh.... why can he not just be exempt from these duties when he is already fully occupied making the costumes? The other guys do their work, he does his, where's even the issue here? This is a really dumb artificial point of tension.
I really like how this manga is actually about the intricacies of cosplay and why people do it. If this was any other rom-com, it would just be an excuse to dress up the female lead
@Narf It's Gojou's timid and negative personality speaking here. He's too shy and pessimistic to talk about this with the other guys in the class, so he's just assuming everything here, with the worst possible alternative as his default stance, naturally. This is consistent with his personality. However, Kitagawa, the most popular girl of the class, should be marching immediately to the guys to tell them Gojou needs to be given time? She has no shyness problems like Gojou.