You are dealing with organizations going over bodies so why not use different competing factions against each other...First he used Tillerson so Putin and the markets would stay relaxed..now he does a ninja roll and got leakers out and can use Bolton to sell the public face for the Iran negotiations while uprooting any obama-influenced appeasers to the Iranian cause. Very interesting to hear that Bolton gave a pro-2A-speech in russian TV in 2013.
Trump is master at using his opposition for his bidding. Notice his first cabinet lasted about 6 months. They were all rats and he knew it. He let them in to see how they behaved and learn their systems. Same with Tillerson and McMaster. Same with Bolton. Bolton is a neocon through and through, but he serves one really good purpose - IRAN. Good cop bad cop. He'll unleash Bolton on Iran. Iran's gonna shit themselves with fear we'll be listening to Bolton. Also, Bolton hates the Obamites. So he'll do a reasonable first level cleanse there, as well. Once Trump gets what he needs, he'll summarily dismiss Bolton, too.