Their decision not to fix is not the problem, their decision to keep the flaw a secret and sell products with a performance expectation set and then release patches that slow down that paid for performance is.
mitigations=off
Anyone who needs out-of-the-box performance can get it if they're willing to accept out-of-the-box security. Of course that doesn't make these side-channel attacks any less frustrating. For instance the original Meltdown and Spectre attacks were on my mind when I chose to "vote with my dollar" and buy an AMD CPU, only to end up with Zenbleed this year lol