Occasionally the ACLU will surprise.
The athiest scumbags of the ACLU occasionally jump into a few of these public skirmishes and take the "conservative" side strictly as a public relations move. It gives them some ammo to say, "See? We're actually non-partisan." Which is, of course, a lie.
The ACLU hasn't had much action lately defending Klan marches (kind of a stale, passe gimmick for the ACLU these days anyway) so they grab what they can get. I don't know how zealous they'll be with this professor's case, but if it helps them with their PR con job, then that's what matters to them.
Anyway, ping me the next time they take up a "free exercise of religion" case, or a Second Amendment case.