Wouldn’t it make more sense to blow the motherboard rather than the CPU? A compromised CPU without anything connected is pretty useless at boot. The motherboard is what’s connected to all the good stuff.
I think that’s the chicken & egg. If the motherboard was responsible for this, you’re trusting the firmware to validate itself. So this moves the validation a level lower.
It’s an interesting problem. The solution is valid, but it’s unfortunately permanent.