Viri can only grow inside live hosts, they are not bacterium which is what you are thinking of. Masks that are saturated and at body temp can and do grow vast amounts of bacterium,however viri can only replicate inside living host cells. In David’s case it needs live ACE2 receptor possessing cells to bind to and replicate. Dirty masks are a bacterium risk but pose no threat for viri incubation.
Grrr autocorrect. David’s = covid’s
Obviously, you are someone who really knows what he is talking about. That is rare nowadays.