This argument falls flat on its face. There is always infections viruses going around. Covid is not the first nor will it be the last.
Who gets to decide what is okay and isn’t anyway? Some myopic “experts” who barely feel the negative impacts of their prognostications? What about other types of experts? What would “music experts” say about shutting down the piano?
It likely wouldn't be crowded. They have pretty strict rules about the number of people that can gather in any room. Also, these people all live together. They are touching the same surfaces, breathing the same air, sharing the same bathrooms, etc...
But you are right - singing would increase the risk of infection. Still, I think the risks from the current version of the virus to a vaccinated group of young people (who are still required to wear masks!) is small enough that the piano should be available.