Something I am curious about is why it matters in the first place. What you define as genuine exchanges of ideas weren’t requested by the OP and he also never complained that the content of that thread was against his wishes. Since the content also wasn’t breaking any forum rules, according to those same rules the OP’s preference is what matters. I brought that up a while ago and I never got a justification for why it’s acceptable for the administrator to selectively decide what rule-abiding conversation is and isn’t permissible.
Because the thread regularly went off the rails and was a breeding ground for negative feelings, and a big part of that was the useless snark that contributed nothing to the discussion and belittled the thoughts of the target. Not permitting such responses was an attempt to curb the hostility. Note that during the absence of those members who often employed such tactics, the thread was at its most productive and civil.
Deferring to the OP in terms of setting the tone doesn’t mean we’re obligated to let threads devolve into petty squabbles that breed bad blood and infect the rest of the forum. Thread rules are great for giving the OP some control over the direction of their own thread, but they’re superseded by the mods’ judgment in terms of what’s best for the forum.