That is a legal disclaimer to prevent lawsuits.
If you chose to deny physics that is up to you.
But Einstein probably understands it better than you.
Why would they need a legal disclaimer if the masks were effective?
They wouldn't. They need the disclaimer because it is the TRUTH. Viruses are much smaller then the openings that are in masks (which openings in the mask not even viable to the human eye). The load means nothing. Even if only 1% of the virus load gets through the mask, it is still enough of a load to infect a person.
Oh what ever you physics guru.