While I'm sure there are folks that would appreciate the mitigation provided by that package, I'm not sure it provides any mitigation to this _specific_ exploit.

The in-kernel Spectre-v1 mitigations, like:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...

are cheap and ubiquitous. You don't have to turn them on, and they're so cheap you can't even turn them off if you wanted.

Disclaimer: I work on Linux at Intel.