What you're missing is that Robinhood is not the only commission-free brokerage. I'm sure you'd rather have no commissions and 80% of the price improvement instead of no commissions and 20% of the price improvement.
The real problem is that Robinhood advertised they have THE BEST EXECUTION compared to other brokers, set up a Committee to ensure they have THE BEST EXECUTION, and then that Committee somehow failed to notice that Robinhood clearly doesn't have THE BEST EXECUTION because they're taking an 80% cut of price improvement, instead of 20% like everyone else.
Unless I'm missing something the boomer either didn't catch that, or chose not to acknowledge it. As a millennial I'll assume his best intentions and that this isn't an attack on a successful company business model that he's receiving a kickback for to de-legitimizing Robinhood.