Venom is a protein that is broken down when ingested. It is a toxin that is only deadly when injected directly into the bloodstream. In fact that is the definition of "venom" AKA a toxin that is injected . As far as I am aware, consuming a venom will not cause harm (I don't know if that statement can be made 100%, but at the least its toxicity will be substantially reduced).

Releasing a protein into the water supply sounds like a very inefficient way to poison people, given the size of water supplies and the amount needed to cause a sickness. However, it would be many times less effective (or completely ineffective) if it were not poison but venom for the reasons stated above. For a venom to get in and do damage you have to get it into the bloodstream intact. That lies somewhere between non trivial and virtually impossible when you ingest it, especially in the small amounts that would be in the water supply.

I skimmed through part of what Dr. Ardis (a chiropractor, not a biologist) had to say about it. What I saw (though again, I only saw a small part) was him talking about COVID having a Snake venom component. It's not impossible that the Spike protein used part of a venom sequence. I'll say that's plausible, though I'd have to see some evidence.

That would not be why monoclonal anti-bodies aren't used though, since each one is specific to the target it is causing an effect against (in this case an immune response). Monoclonal anti-bodies can be used as a helper for an immune response for anything (including a SARS-CoV-2 spike protein), not just snake venom, and each one is specific to the target protein.

In any case, even if its true that the Spike protein has part of a venom sequence, that is a FAR cry from putting venom in a water supply, which to me sounds like complete bullshit for the reasons stated.