How would AnCap deter jihadists from acquiring nukes? Or anyone else who would value the nuke more than their own lives? Restitution is capped at one's lifetime income.
One question is what motivates current "jihadists" to do what they do ? (that seems to be that their competing jihadists, also known as governments who likewise are willing to sacrifice lives of own soldiers for political or ideological goals, drew lines on maps and claimed by force "these are your borders now sucker". Not saying any of those 2 jihad groups are justified, they're both acting like small children fighting over toys, but if it wasnt for the governments interfering in their affairs the jihadists would find something better to do).
Keep in mind that the 2 main sponsors of "Jihadi groups" are the USA, and Russia. With some of their subsidiaries co-sponsoring, such as Iran, Israel, etc.
So how would ancap resist NGO jihad from aquiring means to cause lots of damage, the same way it would resist a Government-form of jihad. Social pressure, few ppl would trade with you if they see you aquire stockpiles and/or if you have a history of bullying. You'd have to pay a premium for your reputation, in other words the rest of the world would get their weapons cheaper than you and you'd never get to the point where you can do any damage.