Re: NASA
More to do with charged particles dashing through the chips. Larger transistors at lower frequencies have much better radiation resistance. And differing frequencies can help to reduce interference, as you rightly noted.
ECC (if done correctly) will not miss anything. Rowhammering needs several write cycles to flip a bit, but ECC logic has to compare checksums on every RAS/CAS cycle. If one bit is off, it can be corrected. If several bits are wrong - checkstop.