Neville- Finally! A constructive discussion. Mainstream halacha in the US, following R’ Moshe and the M”B amongst a overwhelming majority of poskim, hold that it’s a derabannan. Thus, a shita that it is a deoraisa, while it may have a logical basis, has no place in the public discussion of buying beer near NYC after pesach.
As to your statement that “the ‘irresponsible position’ that you reference is not coming from me, but from several mainstream kashrus agencies,” I have a few thoughts: 1. Is it possible that it is both you and the kashrus agencies? 2. Don’t you find it interesting that the only time this information was released was *after* a sale was made? I suspect that the information was *rightfully* withheld from the public as a nonactive way of following the correct halacha. 3. I have yet to see *one* kashrus agency which says that an individual may not buy any of these brands of beer from any store (the Star-K’s unusual position regarding certifying products going through institutions selling chometz notwithstanding).
A kashrus agency’s power lies in its fact-finding boots on the ground, along with its rabbinic guidance. When an agency’s only proactive statement about something is on a podcast, it kind of loses its gravitas. Now if Rav Shechter signed off on an official OU statement that every bottle of certain brands of beer *may* not be bought unless one is *certain* that it is not chometz sheovar, that would be a different story. That hasn’t happened, and I believe it won’t, for good reason.