I think it is an over-reaction. Brenda didn't say Geno doesn't have to coach (when he has 9 AA) she said he doesn't have to coach like the rest of us.
Big difference.
She has a point.
At the risk of over-simplifying, Frese has to do the following analysis:
"My AA Thomas is tired. Should I put in my sub, who isn't an AA? At 100% Thomas is better, but Thomas is tired, Is the sub, who is not tired, more effective than a tired Thomas? Maybe yes, maybe no. My other AA picked up a second foull. Dare I leave her in, because her sub is definitely not as good. Or take her out, because I can't risk a third foul in the first half."
In contrast, Geno analyzes as follows:
"Stewart looks tired, send in another AA. Hartley has a couple fouls, send in another AA"
Yes, I know I am oversimplifying, as Geno is not that cavalier about substitutions. A lot goes into it. Maybe he will leave someone in with 2 fouls because she should learn to play with 2 fouls. Maybe someone should stay in when tired, because it is good to see what it is like to play when tired. No big deal, we are up by 20.
The point is not that Geno doesn't have to think. I guarantee he is thinking harder than the opposing coach. The point is he is thinking about different things.