$1MM salary,
taxes in CA leave you with $570K. Probably gets ~50% of the 12.5% california tax back because you're working in other states half the time, but then some of those states also have taxes, so maybe he gets back roughly $30-40K, make it an even $600K.
Escrow payment is what, 17%? I don't know, but that's another $170K that you don't even see, and you may get back, maybe not. $400K in take home pay is a lot of money for a normal person, but it's not so much that you would be insane to turn it down, because his rent in SJ could be $100K and then...
At college, he's living for free and he's a Chipotle athlete and probably makes $100K in NIL (BC is a rich school, rich donors -> NIL payments... Rumor has it that even depth players in college D1 football make nearly $100K/year, I can't believe BC Hockey stars don't make that much).
So that's $300K in takehome pay after rent, vs. $100K in takehome pay with no other living expenses and living the time of your life.
Plus, it's not like his development is going to get hurt. He may play better in year 1 of his ELC, and that may knock on to his first big contract.
Plus, as others have said, he could burn the ELC year anyway at the end of next year.
I agree with the rest of your post, lots of reasons to stay, but Smith is a Communication Studies major and it sounds like the school work is... not significant (podcast appearance talked about basically him, Leonard, and Perreault being stage hands for some performance for credit). And therefore the studies are ... not meaningful.