> Our civilization desperately needs a method to modify modern microelectronics

Micro is now nano, not amendable to modification, and even if it was theoretically possible, hardware is a super-easy target for legislation.

> Alternatively, just make it illegal to ship any kind of initial bootloader as part of a CPU's/SoC's mask ROM

If you had the political means to enact such legislation, you could legislate much cleaner and easier ways to deal with the problem.

I find myself saying this a lot but I still can't quite figure our why people keep seeking technical solutions to political problems.

I mean, these things aren't comparable, in some limited cases the naive approach might help but insisting on it while neglecting political action is worse than doing nothing.