It's amazing when cultures are so bad that people whose sole job is recruiting fail to follow the most basic federal regulations involved in their job (assuming your situation was in the US).
If you're going to be awful, at least...don't obviously violate federal law while being awful?
This may not have been a violation. Age discrimination is only illegal if the person is over 40. You could easily be “culture fitted out” for being mid-thirties when everyone at a startup is early to mid twenties. And yes, it really is that bad in SV (or at least was pre-COVID, not sure if anything has really changed).
That's federal - some states have laws protecting people less than 40 as well. Also, fun fact, but reverse age discrimination is 100% legal in every state. It's entirely legal to say "We gave X the job because he is 55 and you're only 45", but it is illegal to say "We gave X the job because he is only 45 and you're 55"
If you're going to be awful, at least...don't obviously violate federal law while being awful?