Ryan is backing Nunes. Without Ryan's support, Nunes doesn't get past his orchard in Fresno. Ok, next question: Why is Ryan - of all people - backing Nunes?
Glad you asked; the answer is Trump. Whatever Trump has promised or threatened, Ryan is fully on board. So, using the associative rule, we can remove Ryan to deduce that Nunes = Trump.
Since Nunes is actually Trump, then why would Nunes have anything to fear from Brennan, et al, when he has the full backing of the DoD to clean the swamp? Hastings was an early pioneer/scout; as such, he literally ended up with arrows in his back.
But Trump is the cavalry. These things take time - don't ever forget the entire purpose of the 2018 long reveal are the congressional elections. Trust Trump. My doG, he's done this much so far - how did he do it? Dumb luck?
Nunes is a courageous man and is doing a good job.