I don't actually thing you'd manage to swallow any of the molten iron...

Based on the posed question and its limiting conditions, elemental mercury is a correct answer. Pure hydrogen peroxide or isopropyl alcohol would qualify, too.

If you include materials which are liquid outside of "room temperature," things like magma and liquid nitrogen would also be correct answers.

Not quite, actually! I mean, it’s not good for you, but once it’s in your digestive tract it mostly passes straight through rather than being absorbed. The vapor over the liquid is more dangerous, but once you’ve swallowed it that’s not a concern.

that's exactly why this is the right answer

No I'm not.

I posit that any substance which can be ingested as a liquid by pouring it from a container into one's mouth (the act of "drinking") is, by definition, a "drink."

Supposedly, gallium is non-toxic, and liquid at body temperature (though not room temperature).

I think OP knows exactly what they mean, I think if you asked a five year old they’d know what they mean.

Yet for some reason, some people are completely missing the point of a very simple question which boils down to “if you couldn’t drink regular water, what would you have instead”…

The point of OP's question is clear. He's referring to a drink that has sensory qualities that are clearly distinct from plain water. Water with a spritz of lemon still reads as water. As a loose guideline this is like anything you'd order as "water with x" or "x water", like cucumber water. Coffee clearly doesn't fit into that category, it has sensory qualities that are very different than water with x in it.