I think what they are arguing is that you should only get one or the other -- that there should be no trade secrets required to put a patent into practice after it expires.
Lots of research and methods related to covid-19 is not patented.
That's the problem. Patents aren't useful to the public because they don't describe enough to make a useful product when combined with public knowledge. The monopoly granted is supposed to be in exchange for expanding the public knowledge after expiry, but if most of the knowledge is kept secret, then the patent system isn't striking the bargain it was meant to strike.
