But the viral property that makes this attack so insidious is, in the end, not sufficiently viral: the compiler will eventually drift away (as a consequence of it being developed further, of course) from the patterns it recognizes. The attack is not as dangerous as it sounds.
I'm not really arguing that too much, since it's a pretty elaborate and finnicky thing ultimately, although I would wager to say that you could probably find patterns to recognize and modify clang/gcc/other relatively stable compilers for a long time to come (assuming no active mitigations against it)