OK, first off, your "resistance" is a bunch of disconnected people who don't like to communicate and have no way of identifying each other
All resistance movements share those communication & identification issues. This is a hurdle, not an insurmountable barrier.
Secondly, if you really think your retired demolitions buddy can walk onto a military base alone, obtain explosives sufficient to obliterate a building
No, while he still has access to military bases, he probably could not access a munitions storage area without help as things are today. The question is open, though, whether such a level of security would remain intact und the LeShay's rule.
In "This Side of Paradise" the crew of the Enterprise, enthralled by alien plants, abandon their positions to live planetside. This leaves the ship and all its resources unguarded.
While I doubt the LeShay would have troops stand down completely, the guards in question may not be as vigilant as they would be. Their minds would expect anyone approaching to be as loyal as they are, as opposed to the suspicious minds of the unentrhalled.
Just as people have questioned whether someone would use an IED on someone they thought a "friend", the question is just as valid here- would an enthralled guard be disciplined enough to shoot someone who is supposedly just as besotted by the LeShay as he is?
As for my buddy, I know he could make an OKC device, though.
You and I know that it is possible to make such a device with materials common to farming. We also know that certain materials even contain unique plastic identifying beads so they can be tracked to individuals.
But this is an alien concern, probably outside the LeShay's experience. He would have to ask the right questions to recognize the threat.
Fourth, if we're just going to make up random bad stuff for the LeShay to do
The LeShay can be ANY alignment.
One who is LN may deem drugs a hedonistic scourge and attempt their eradication. One who is CE Might engage in genocide. Etc.
we might as well throw gas rationing and travel papers into the mix
If I were a LeShay, I probably would. But that just makes things difficult, not impossible.
Familiar with it- VERY familiar. What's your point?
Just because someone is willing to do great evil in someone's name if they think it is for a good cause/they're trying to follow instructions, YOU won't quietly accede to extinction unless you yourself are in the "fanatic" mind state.
Not only that, while the Milgrim experiment's results are pretty horrifying, we also have RW counter examples from the very regimes that inspired the experiment, illustrating that it is possible for people to disobey authority in the face of death.
On top of this, there seems to be an underlying assumption that someone can be a fanatic about only one thing at a time. Admittedly, this is at least in part because of the way the skills are we printed in D20- there is no consideration as to what happens when someone is trying to convert a fanatic to a fanatic of opposite intent. I don't know about you, but I already have things in my life I would be willing to die for.