"A very modest salary cap" works if your mission is planting trees. Not so much if what you're building is frontier AI systems.
If a non-profit can't attract people not motivated except by profit, perhaps it shouldn't exist.
While I agree, if you need high profits to survive, you're not off to a great start as a nonprofit.
I think that's the point though. The AI companies can't compete without hiring very talented employees and raising lots of money from investors. Neither the employees nor investors would participate if there weren't the potential for making mountains of money. So these AI companies fundamentally can't be non-profits or true B-corps (I realize that's a vague term, but the it certainly means not doing whatever it takes to make as much money as possible), and they shouldn't pretend they are.