So the actual thumb piece screws in? Looks like you have your screwed out a little ways. Does the release come with any shorter bars that thumb piece mounts to?
LOL actually that's how mine came. Yeah the thumb button screws onto the shaft and is secured by means of a tiny set screw; thus you can change the angle of the thumb button. So looking at the third pic
@Red Beard posted you could rotate the thumb button on the shaft/post so it's sitting at more of an angle. I might back mine out a bit more as I have pretty wide hands. No, it doesn't come with any other shafts/posts but if you were careful you might be able to machine so more threads onto the included shaft and then cut some off to make it shorter.
Here's a couple more pics showing how it fits in my hand. I have the button pegged all the way to the rear as I like it buried in the web of my hand.