Even if they could've argued that they themselves were fooled by the seller initially, not following up after the guy was killed points to a much bigger issue. Basically they just don't give a shit.
Side note: I'm filled with dread just thinking about buying a motorcycle helmet from amazon.
Buy it from a reputable source? There are specialist stores herearound, which sell nothing but helmets and have staff on payroll with an actual clue.
Sure, you actually have to leave the house. In return you get the possibility to actually try the helmets on display.
If price is the issue I think it's exactly that general attitude, which triggered that downward spiral in quality we're observing in the last few years.
But there are tons of other items that you either can't go someplace and purchase them (at least here in the USA), or if you can purchase them in some manner, you'll end up paying 5-10x or more for the privilege.
My goto example is DC gearmotors. There are plenty of USA based manufacturers and suppliers of such. One great brand is Ametek. Unfortunately, you're going to pay for that privilege. A motor I might purchase via a vendor that is made by, say, TSINY motor (a good chinese brand I might add), will only cost me around $15-30.00 each. An equivalent motor from a USA vender and/or manufacturer? Multiply those numbers by 10 - easily.
As a hobbyist - that's just insane.
Don't, I wouldn't. Revzilla, sells all sorts of motorcycle gear and has a great reputation. https://www.revzilla.com/
He probably saw the writing on the wall for the North American moto business with the boomers aging out and not enough consumers left to support the operation long term.
The most likely explanation why they would not remove the listing in a regression-safe way even after getting dragged to court is that the team dealing with the lawsuit is paid for being good at lawsuits, not for avoiding them, while the team responsible for managing third party listings is paid for snacking third party listings. It's almost surprising that the listing apparently did disappear while the court was watching.
Put all this into an organisation that has a multi-decade tradition of sidelining mundane, conventional company goals like striking a profit in favor of enigmatic founder strategy and nobody will ever risk rocking the boat by pointing out problems outside their job description.