You can't call on members of the community to sign an "anti-racism pledge," just like you can't call on them to sign a loyalty oath to American capitalism. Of course, this isn't quite as bad as mandating as a condition of employment a profession of loyalty to the ideology of anti-racism (whatever that is: "I won't join the Klan," "I won't use racial epithets"?, "I won't disagree with Black Lives Matter?"), but it comes to the same thing: after all, the President has issued a public call for signatures, his staff has duly signed, so who would want to risk being branded a "racist" for failing to be counted? But there are plenty of non-racist reasons not to sign: e.g., doubts about what will count as "the conditions and structures" that allegedly support bigotry, doubts about who one is being asked to "stand in solidarity" with and doubts about their conceptions of "justice." No one, least of all this blowhard President (who sounds more like the former politician he is), knows what it means to be an "antiracist...in all aspects of your life." That the President goes on to quote the totalitarian wannabe Ibram Kendi certainly does not inspire confidence.
This kind of thing generally cheapens the idea of anti-racism. Universities are rather sad and pathetic places, in general. They're the kinds of places where, when people claim to get worried about racism, rather than using their ample resources to combat serious problems of racism out there in the world, they instead just hire a bunch of diversity officers who then create milquetoast programming for their student bodies, who already tend to be relatively non-racist and anti-racist. It's like getting worried about starvation, so you then distribute extra snacks to your generally well-fed student body rather than trying to feed actual starving people in refugee camps. You have to wonder whether the point is not to combat racism, but instead to be seen as anti-racist.
I mean, consider: If you had $1 million to spend to fight racism, would it make sense to use any of it to do anything at, say, Princeton University, or even the University of Southern Maine? These are some of the least racist places in the US. If you can't come up with a better, more effective use of that money, you aren't trying very hard.
But, beyond that, it's pretty bogus for universities to ask people to take any kind of ideological pledge, even for the correct ideology. If Georgetown asked its faculty to sign a pledge affirming that they agree with everything that I, Jason Brennan, have published, I wouldn't sign it, even though everything I've written is of course correct and of course everyone is morally and epistemically obligated to agree with it.