Yes Boone will because of his sour hatred for legion also he warns you about helping them and if you do get idolizied he will probably attack you.
- Well I'm already Idolized by the Legion and have recruited Boone by wearing an NCR faction armor. As soon as I recruited Boone, I took the armor off and he immediately warned me about working for the Legion BUT he still travels with. My question originally related to when Alerio/Vulpes gives you the Caesar's Mark and talks to you after leaving the Tops. I still haven't completed the quest "Ring-a-Ding-Ding" yet, so what ever happens, happens... The same guy to asked the question by the way.