I think he means professional virologists and other credentialled professionals to "debate" on a subject like communicable disease spread... VS just some dudes chatting on the internet or on a couch somewhere.
When you say, "There is still serious debate whether masks are even effective." ... the "serious" part seems to indicate that there are differing groups of credible researchers out there. That is something I have not seen.
"Serious" research is usually co-signed by several who agree with the findings. I would love to see a citation from a cadre you can bring up here. I
SWB, most including me agree with you.
Put how can you possibly support that there has not been or still not a debate on the effectiveness of wearing masks.
They are still debating that issue, but I guess the medical and scientific experts that are arguing a settled issue. because you believe so.