FYI, "apologist" is often not used to literally mean "one who apologises", but rather "one who defends"[1], with a negative connotation (at least in my experience).

I would guess the "C apologism" in the original comment is referring to defenses of C that pretend C is safe "in practice" (or "for people who know what they're doing") or minimise/ignore the strong correlation between the use of C and serious problems/vulnerabilities.

[1]: https://en.wiktionary.org/wiki/apologist