You seem to be conflating two things. People who give logically bad arguments for their positions, and people who say things that trigger listeners absurdity heuristic.

The more radical positions tend to be more logically coherent, hence easier to logically defend. On the other hand they're also more likely to trigger people's absurdity heuristics.

More moderate positions are harder to defend since you wind up jumping through hoops to explain why your logic doesn't apply to certain cases. This means that in practice the more moderate position functions as a Trojan Horse for the more radical position.