What stood out in this tweet for me were three things:
1. A willful refusal to acknowledge that if you have two priorities, two axes, so to speak, on which you base your hiring decisions, then it is entirely possible that one of the axes will impact decisions that could have otherwise been made entirely on the basis of the other axis. Or, graphically, if the decision to hire is the area of a triangle, one of whose legs is plotted along the "diversity" axis (y) and the other along the "merit" axis (x), these two triangles should have the same area leading to the same hiring decision. And what the CEO is saying, effectively, is that, if given a choice, he would always prefer the second triangle:
2. Claim that the lack of diversity lowers the hiring pool. I understand how that might happen if the company is aggressively biased against the minority candidate ("we don't hire X"); or if the minority candidate actively resents being in the minority and therefore does not apply; but if we are dealing with a rational company looking for "merit" regardless of where it's coming from, and a rational candidate looking for a job opportunity, this should not be relevant. (Yes, I know that according to behavioral economics, market actors are not rational.)
3. An immediate jiu-jitsu move transforming the argument into a personal attack, very much in the spirit of Twitter: "if you dare to speak the things that you said you are incompetent". The phrase "an okay thing to say out loud", implying that you can think that something is reasonable, but you should dare not speak it, makes me angry.
So that's the tweet. What vaguely resonated with it was the phrase from a conversation between Glenn Loury and Charles Murray, in which Murray says:
In a way, the whole civil rights thing was handed over to the lawyers. So, if you are an employer, it was no longer "we never even bothered to interview blacks before; come on, we've gotta reach out and find blacks who want this jobs and interview them and hire them if we can"; it changed from that to "we don't have enough blacks; the EEOC is gonna be coming down on us, and do we have enough to be safe"?
I was happily unaware of the existence of the EEOC, as I am mostly ignorant of the whole civil rights movement and its consequences; but I can imagine how it can create perverse incentives with the implications relevant for the topic raised in the tweet.