AITA for refusing to fix my client's electrical problem for free after he rejected my written recommendations?

I've been a licensed electrician for eleven years. About four months ago I did a full kitchen renovation for a homeowner (52M) who wanted to run a double oven, a wine fridge, and a restaurant-grade range off his existing 100-amp panel.

I told him three times that the panel wasn't rated for that load. I explained it would trip breakers, potentially void his appliance warranties, and could be flagged by his homeowner's insurance. He said he'd looked into it and to just do the job as quoted. I had him sign a written acknowledgment that he'd declined my recommendation to upgrade the panel. I keep those records for exactly this reason.

Last month his range and wine fridge started tripping the breaker on the same circuit. The appliance warranty rep told him it was an electrical issue, not a product defect. His insurance adjuster flagged the panel during a separate claim inspection. He called me demanding I come fix it at no charge because I "should have known better than to let him make that call."

I sent him the email chain and the signed acknowledgment. I told him I'd upgrade the panel at my current rate $185/hour, he supplies the parts. He posted a one-star review calling me "reckless" and has been telling people in his neighborhood Facebook group that I do shoddy work.

My wife thinks I should have pushed harder at the time, or at least offered a discount now to make the review go away. I think doing that sets a terrible precedent. He signed a document saying he understood the risk.