The “paradox” here is that by being tolerant of intolerance, we are actually decreasing the overall level of tolerance when normally we’d expect tolerant behaviors to increase tolerance.
Compare it to the “death wave.” When someone stops in a multi lane intersection to allow someone to cross in debt of them, the pedestrian/vehicle can’t see around the stopped vehicle and this can result in them being hit by a motorist in the adjacent lane. It feels like you’re being safe and considerate, but you’re actually putting the other person in more danger than if you had simply followed the right of way. It happens often enough that a name has been coined for the phenomenon.
Tolerating hate increases hate, not tolerance. Tolerating hate in the extreme decreases tolerance not only relative to the hate, but because once hate takes over they eliminate tolerance (see Florida).