I read it.
Well, as Gan Honorary History Master and Kozenshi said, I think there is still a possibility of a cold or influenza. Certainly, it may be against manners to keep the sutras while wearing a mask. That said, I sometimes wear a mask this season in my daily life. Also for prevention.
Last year I caught the flu and had my funeral extended by about 5 days. The schedule was adjusted for the time being based on the doctor's diagnosis, but since it was still not long since I was healed, I was able to wear a mask for all of the Makura Sutras, vigils, funerals, and cremation ceremonies. At that time, I explained to my relatives, the funeral home, and everyone attending that I would wear a mask to work, and I obtained their consent before doing the work.
Maybe that monk cared about everyone too. If I see you next time and still wear a mask, they'll say, “How are you? They're wearing a mask, so why don't you talk about “I wonder if they have caught a cold etc.”
After talking about it, you might understand the reason and think it's ridiculous that you're not convinced.
I sincerely pray to the Buddha that everyone will make a memorial service for their mother with all their heart.