There was a choir practice that was a super spreading covid event. Dozens of infections.
It makes sense to me.
It makes sense to the very high majority if not all of the health professionals as well.
There are numerous reports that yelling which is involved in singing or speaking loudly can have droplets they emit spread a further distance.
There are also numerous super spreading cases associated with singing and nightclubs/dancing. There was a case in South Korea that one super spreader was if I remember correctly at one point linked to 90 cases of the Coronavirus.
There was also another case in Washington where a choir had a rehearsal and almost all of it's members became infected with a couple dying.
53 of 61 people who sang with the Skagit Valley Chorale in March were infected, and the CDC says it shows what can happen with no social distancing.
www.businessinsider.com
Taken the above information into consideration it's very easy to understand why singing is banned in restaurants.