The quote mentioned that store-bought masks don't prevent infection. He didn't say that they work poorly. The recommendations suggest that having any mask is better than having no mask.
Whether there is any difference between those two assertions depends strongly on your implicit cost-benefit outlook. Liberals typically subscribe to a “any measure even one with a small benefit is worth it.” Conservatives usually feel the opposite.
That is false. He is not arguing, "they don't provide enough benefit to justify inconveniencing people". He is saying they are ineffective, which is an intentional sleight of hand argument that focuses not being effective in blocking the virus from being inhaled while ignoring that they are effective at reducing the velocity of airborne particules when exhaled and distance at which the virus can be transmitted to others. Which, on the aggregate, is effective.
It is grossly dishonest and as a surgeon, he knows this. It's filthy, disgusting political strategy that is killing people to try work a wedge issue for '22.
https://www.paul.senate.gov/news/dr-rand-paul-introduces-leg... is further proof that he is not entering the public debate in good faith and in service of public health. We have not reached herd immunity, and had not at the time he introduced this. As a member of the Committee on Health, Education, Labor and Pension as well as Homeland Security and Government Affairs, there is no doubt he had access to to better data on this than the general public.
I would love for him to say "I am a conservative and I'd rather some people die than to even allow the mildest mask laws" so we could have an honest debate. He wants to frame this as an individual freedom question, and wants to deny the deaths/illness that are the consequence because it harms his rhetorical position - or really, his future career in politics. That might raise the idea of an individual's right to not get sick and die as a result of someone else's decisions. We do not allow people to drive intoxicated in the US for this reason, as well as a host of other regulations.