First, the term “intellectual diversity.”
This is an argument conservatives have been using since late in the last century: the left says it wants diversity on campus and in business. They push for racially diverse faculty, openness to hiring women in media — but where is the intellectual diversity? Why aren’t they hiring more conservatives!!! If they really believe in diversity, they’d hire conservative teachers and tolerate them saying conservative things! And hire conservative pundits for the newspaper (the NYT hiring David Brooks and Brett Stephens [who argues that “Falsely accusing a person of sexual assault is nearly as despicable as sexual assault itself.” — no, no more than a false accusation of murder is as bad as murder] isn’t enough).
I will admit I’m biased because I think conservatism in 21st century America is just crap. But even allowing for my personal biases, intellectual diversity is not the same as ethnic, religious or gender diversity. Conservatives do sometimes get the shaft, but there’s no history of systemic discrimination against them the way there has been against blacks, Jews, women, etc. Hell, there’s never been anything comparable to the 1950s blacklist which purged communists, socialists and somewhat left-of-center people from Hollywood and countless other jobs. That Kevin Williamson lost a a gig at Atlantic because he thinks we should hang women who get abortions does not represent a crime against free thought — it’s not even the dumbest thing Williamson has said (did you know Obama having two daughters makes him less manly than Mitt Romney’s five sons, which is why Romney would totally crush him in 2012?).
Second, the use of “gatekeeper.”
When I first started hearing the term a few years ago (in any sense other than literal) it referred to people who control access to something and abuse their power. Harvey Weinstein, for example, who pressured or assaulted women for sex and used his influence in Hollywood to shut them out if they pissed him off. Sherman Alexie in the Native American writing world. It also meant people who thought they should have the clout to control access, like the male comics and SF fans who rant about “fake geek girls” as if they (i.e. the fans) can decide who is and isn’t a real fan (of course people have been doing that for decades, but when it’s specifically gendered or race-oriented it becomes something nastier).
More recently though, the term seems to have turned into mush. Martin Scorsese saying he didn’t think Marvel movies were art was being a “gatekeeper” according to one dude in an online discussion. Telling someone Wikipedia is not a satisfactory information source is “gatekeeping” (this was in a context where the first speaker had no authority over the Wikipedia-user at all). It’s much like the way “Mary Sue” has gone from “idealized version of the author” to “any character who’s more awesome than the rest of the cast.”