I guess we'll just have to wait and see how this plays out.
What made we wary of General McMaster is that he was one of the few Trump appointees that the GOP establishment seemed to approve of (along with transparent party hacks like Reince Priebus and the shrill non-entity that is Nikki Haley). They hate Bannon and Miller for obvious reasons, they attacked Tillerson for being on good terms with Putin, Sessions was a "racist" to them, and the neocons disliked General Mattis for some reason (he wasn't pro-Israel enough for them, apparently), but this same crowd had nothing but praise for McMaster.
I knew a good bit about McMaster long before he was put forward for NSA. Read his book, watched interviews and talks on youtube. I’m certain that most of his newfound critics are far less familiar than that. I never saw any evidence that he has a political agenda, much less one hostile to conservatives.
I grew up around the military. In my experience many military officers are far less politically aware than you would expect, particularly with domestic politics. They know their own field, they know internal service politics. But their focus on foreign policy is different because they are constantly working with foreign govt’s and to them it is very important that we have good relationships with our allies.