It's partially an off the cuff response, but like all good off the cuff responses, it's meant to cause the reader to think a little bit deeper about the message. I'm glad that you didn't find it beneath you to respond to it as it was not intended to be dismissive of response, nor was it thoughtless.
Many of the FAANGs have pushed for diversity in hiring. I don't have a problem with that. I think an ideal workplace would hire people regardless of their circumstances of birth and lived experience as long as they are qualified to do the job and they, in fact, do a good job there. That's actually the crux of my problem.
When companies have pushed to remove names, genders, and races from resumes before the hiring process because they find that people are treated differently in hiring due to unconscious bias in that process then it smacks of hypocrisy to then blanket filter incoming resumes unless you went to a short list of approved schools or have a buddy on the inside juicing your chances. That sounds like the complete opposite of trying to be diverse in recruitment. I don't think that Lambda School is that great of a response to this - it just adds one more "acceptable" school to the list.
In fact, to a cynic, it sounds like virtue signalling of the highest order to please both Wall Street and the public.