[merakses]

The only individual we've seen materially aiding Makishima in his actions is Choe. And THEY'RE childhood friends. And some of the people Makishima has devoted quite a bit of time cultivating (the psycho lesbian school girl) have very little arguably to give to any kind of revolution in terms of skills or resources.

Senguji was fairly close with Makishima, and he was chairman of the Teito Network Construction corporation. He said the following after killing Rikako:
"It seems you were a fox cub providing entertainment, but just like him, I'm one of the players who enjoy that entertainment."
Makishima spent much more time in direct contact with him than with Rikako and Mido. Their relationship was different than that between Makishima and his pawns. Also, Senguji is one of the players. There might have been many more. Finally, those players were probably the ones who enabled Makishima to create and mass produce the helmets - since he is unlikely to have had all the necessary resources to do that by himself.

If that's the case, wouldn't destroying the Hyper-Oats NOW go against his desire to give people a chance to express their free will?

Destroying the Hyper-Oats will still eventually give at least some people the chance to express their free will. Under Sybil, everybody have given up their ability to choose and simply wait for the system to give them an answer. (at least that's the way he thinks)
To put it bluntly, directly destroying Sybil (and mass riots) > destroying food supply (and mass starvation) > leaving system as it is.

Makishima mentioned he'd have been completely happy with total anarchy as a result of whatever they did in the tower. I don't think he's concerned at all about collateral damage. Going into the tower really came off more as doing a favor to his buddy Choe who was curious about what Sybil was (as was Makishima).

Well, he certainly was curious, but I don't think it was the main reason. Once again, total anarchy would have been a choice taken by the people; starvation wouldn't. As long as people were free to make their choice, Makishima would be content - regardless of what that choice turns out to be.

Why does it have to be exclusionary? Can't we just say that he was both a revolutionary and a homicidal maniac? Or perhaps a revolutionary who also revels in violence?

Because every time we've seen, the violence has always been the means, not the desired end. Some quotes from episode 15:
"It seemed as if he was always trying to find answers through his crimes"
"If he was a criminal who'd find enjoyment in watching a riot like this, we could have arrested him more easily."

I would argue that Makishima is acting on more than one interest here - not only is he against the system and thus seeking to destroy it, he is also interested in what humans would do with the violent impulses that Sibyl suppresses.

Still, that makes the second driving factor curiosity, not desire for random violence.