Maybe I'm not understanding your objection clearly, but what they wrote was "...prevent people from pursuing a hate-filled, violent life or convincing them to abandon such a life"
I think this is pretty careful sentence structure on their part to suggest that it's normal people who enter into such a life, not that they are at their core hate filled and violent. The section seems to agree with what you're suggestion, and maybe it's just awkwardly worded, but as a native speaker, to me it sounds like the usual deescalation tactic of affirming the goodness in people. "Life" may be causing some misunderstanding or changing the scope slightly, but it still fits.
Is this accurate or just another easy way of saying "these people are not human they are just evil"
Is it both more accurate and more frightening to allow yourself to think that terrorists live a generally peaceful and happy life within a family? Aren't the worse monsters the ones who live amongst us and not the ugly other?
I suspect it is and that makes the solution harder on some ways but also easier in others. If your brother can fall into thinking one way then he can change his thinking and move into another way.