Terminal C had Pre-Check at one point, think B had it also at the same time. Then it went to B only. Annoying but makes sense with summer travel. Terminal C security is more compact so dedicating it as Pre-Check only makes sense. Less options for infrequent travelers who tend to block the pre-check access.

Problem is AA counter orientation. (Unless they've changed it). Elites have to cross check-in area but so does everyone else. If non pre check eligible still check in at C they may still try to utilize escalator and block access. Expect orange shirt presence to increase.