No kidding. When did Republicans become such whiny pussies? Though they're happy to dish it out, they sure can't take it. Every little slight, real or invented, sends them into a sputtering outrage.
Professor Lewin's e-mail was inappropriate, no doubt about it. As a professional and as a role model to students, she should hold herself to a higher standard, especially in any communications that some might interpret as official (even though it was apparently meant as a private message).
Beyond that, who cares? It was a stupid remark, Lewin issued the mandatory "apology" she obviously didn't mean, and if she has a clue, she learned to think next time before she hits <Send>. Presumably her boss told her STFU next time, if only because she should have known the usual cry babies would get all butt-hurt about it.
If she simply cannot hold her tongue, however, I'd suggest in the future she stick to Republican-approved retorts, like "Go fuck yourself." Then, when she has to apologize to the same people who dismissed Cheney's slur as no big deal, she should sincerely reply, "Grow a pair."