Maverick's confident. Indrik's stupid, which means he can be easily manipulated, which means having a visual example to compare himself to would trigger some kind of superiority or inferiority, or something. Also he really doesn't want to go into how he doesn't really want to picture Indrik trying to fuck his cat, which is what the immediate association with 'asserting dominance' is. Good thing he's distracted by something far more important: cats.

"Whaaat? Why the fuck don't they like you?" Maverick likes Rex, therefore cats should like Rex???? because Maverick loves cats? The logic breaks down somewhere, which is why he's glad he's not stupid enough to say it out loud, but he still thinks it.