I find the rebuttal kind of badly formed. The OP claims that a 10 foot difference would kill all life. The rebuttal claims that the Earth already experiences way larger swings. I guess I feel that the rebuttal isn't really a rebuttal. It's just saying "you're wrong, here is what's actually true" without really providing a convincing argument. To an uninformed person neither is really a stronger claim than the other. Maybe a reference to an authority would help? Maybe that'd just make them sound like an asshole...

Additionally, I think bringing up AUs just muddied the rebuttal with unnecessary jargon. The goldilocks zone wasn't bad, but they could have just directly said the Sun's habitable zone is X to Y miles; a range of Z million miles.

And the earthquake claim feels like it came out of nowhere without any explanation. I'm not familiar with why an earthquake would knock us 10 ft out and I can't really figure it out.