I've felt that way from the beginning.
It may be that the publicity has made Greer relatively safe. Killing him now would confirm his story.
It may be that he's a carefully trained and planted stooge of the puppet masters still working all sides of issues and setting the populace up for some gradual shifts.
Hard to say.
I am rather glad he's alive and doing what he's doing, however.
Even though I think he's an idiot about thinking all the ET's are wonderful or benign.
Sort of like Jennifler Flowers. She got loud and also got herself a mafioso boyfriend to protect her.