I asked 6 marines who were walking around in full uniform in my town in Australia what they thought of trump last night. They said he's their commander and chief and two stayed silent.

I don't know how you handled it, but you just asked 6 guys to talk about their boss. Them saying he's their commander-in-chief is saying "I'm not at liberty to speak freely." If you were friendly and asked them I'm casual conversation over a beer, you might get actual opinions, but you're asking for trouble if you just go around asking people to shit-talk their bosses.

I live in an area with a lot of military presence. A large number of people who join are just doing it for the benefits. I'm sure you're aware, but normal citizens don't get free college or Healthcare (in fact, it's incredibly expensive), but if you sign up for the military they pay for college, you get socialized Healthcare, they cover housing, and a lot more. Most aren't doing it because they love Trump, or even out of patriotic duty. They're doing it because shit sucks, and it's an option that gets them out of a hole. I'm generally anti-military (particularly in the US), but I don't hold it against people. Most of them don't like Trump, in my experience. He does not have the support of our military personnel, and I'll welcome them if shit finally breaks down and they abandon the state.

I asked them kindly to fuck off put of our country because they're not welcome

First, they literally are welcome there. Take that issue up with your government. You ask other people to stand up to their government, then you complain about other people's government for what your government does. Second, they don't have a choice. You sign up and you don't really get to choose what you'll do or where you'll do it. See above for why they joined.