I think it's more a reference to Spectre and Meltdown and Rowhammer and a bazillion other hold-my-beer attacks that have never, ever been used in the wild but that everyone pays the price for by having their CPUs slowed down by the countermeasures. Applying Unicorn Repellant is fine when there's no cost, but it definitely has a cost in these cases.

I had read there was a ~5% slowdown with it enabled.