As to a extremely useful post ending up in TalkMail after it is selected by a human editor, that would happen with or without a reader feedback button. No difference.
I suspect there are some people who'd be reassured by a specific opt-out, assuming IB was amenable. (No idea if that's a small or large number.)
I don't know why the ones posting here seem to feel it's more likely if this feature is added; I don't recall seeing ANYBODY suggest that they want some kind of automatic curation based on the likes. I think the potential "gaming" nonsense (though harmless) may actually decrease the odds that it WON'T contribute more likely, as any gaming adds "noise" to the potential value to any automated selection.