Conversely de-radicalization may not be needed.

I think people sometimes over-invest in the concept of redeeming these people. But actually focusing on them and their problems is doubling down on the validity and importance of their positions.

I advocate ignoring them and focusing on creating political power that we can actually use to advance our causes. If they come along, great. If not, consign them to the dustbin of history.

This is complicated when the people involved are emotionally close to you. But in general this is my philosophy.