They were former members in those organizations, like army vets, and as far as I understand they face a lot of criticism from the Israeli public, if not the government.

I think they are basically like those vets that go and work security for private contractors, and some of them end up working for some really bad people.

About the backdoors, I can't tell, on the one hand, I would assume you're correct, that they do provide access to the Mossad+friends, but on the other hand, if it was discovered, they would lose credibility, and all those basically bad people wouldn't work with them, and any normal entity probably aren't working with them already, so they would lose their entire business.