So, I asked John Wick how pressure works on Brute Squads. He looked at me and his eyes glazed for a second, he grasped his bloody mary and blurted, I don't know... it never came up." So we started brainstorming.
The first thing we agree on is that a player SHOULD be able to pressure a brute squad. but with the squad not having actions to spend, they can't really resist which makes for never really needing to ever use them. so this is the potential fix:
When a player applies Pressure to a Brute Squad, The GM may opt to let the Squad follow the command or they may choose to act normally but are reduced by 2 members. (making it slightly more useful than just dealing a wound to the squad in a fight)
I would further recommend a player cannot command a squad to turn on it's villain leader unless the leader has acted in a manner detrimental to the squad previously in the sequence (say setting fire to the room with them in it) but can command them to surrender, stand down, or parley (I hate parley)
SECOND ISSUE: Multiple Pressures on the same target. A group may get it in their heads that if each of them commands the villain to do something different, it will stack up the pressures. I recommend that multiple Pressure attempts cancel ALL pressure attempts. a villain getting shouted at from all sides will probably ignore all of those orders and do what they wanted anyhow.