If you wanted to sue over the fact that these vulnerabilities even happened so badly and were present for such a long time, then okay, but complaining about the companies still selling them between officially learning of the problems and making it publicly known is excessive. The same goes for suing Intel over that. AMD and Intel couldn't have simply stopped selling the chips because the retailers, OEMs, and such would have continued selling the chips or selling products containing the chips.
Maybe recalls would have actually stopped sales, but how can you recall practically every CPU in existence? Besides that, what's the point of stopping sales if you believe you can get workable patches out before much malware actually exploits the problems? If not for the sample code getting published, it might have been even longer before Meltdown and Spectre exploits started showing up.