I should say as a caveat, that my making fun of these guys in no way reflects on my concern for the serious underlying issue that caused them to show up there. Government overreach and abuse of power are serious issues.
That said, this militia group is at this point likely not helping. Perhaps their heart is in the right place, but if you're going to do something like this, you need to plan it through, and that requires planning for PR and public perception of everything you do. Right now, they're beginning to look like the stereotypical liberal definition of "dumbass white guys running around in the woods playing army". You can't help but laugh at camoed out armed tough guys who've taken and occupied an objective, post watches, talk about killing or being killed for the cause, but hey, we really need that French vanilla creamer.
Without knowing all facts, my perception right now is that the government is actually doing something smart (regarding how they handle their side of this) by just letting the group sit there. That visitor center isn't scheduled to open back up until what, May? It's in the middle of nowhere, so really no one is affected right now. If I were one of the govt responders, I'd probably be saying, "Just leave them there and ignore them until they run out of supplies and get sick of camping out".
The fact that the group already released this list of needed supplies tells me they probably thought they'd get a lot more traction in the first days, that there would be some resolution, and that they really didn't plan on spending "possibly years" there. I think most of them figured it would all be wrapped up by now, one way or the other. By ignoring them, the govt takes away all their leverage. At some point, I assume some of these guys have to go back to their jobs, unless they're independently wealthy or unemployed or something.
Possibly BLM and OWS protesters were smarter by occupying and blocking areas that caused aggravation, which caused the authorities to address their demands. Not that I at all agree with the methods those groups used.
A positive suggestion, just so it doesn't look like I'm simply ragging on them and their cause, would be for them to go back to what they did before they occupied the building: Peaceful marches through town, or showing up at the visitor center when it opens with not guns, but signs and literature. Or better yet, do it in front of a regional BLM HQ, or the DOI building in DC where you get a lot more exposure.