I think that thumb screw might be too big. The head is 1/2" across. I can tell you more once I get the Vengeance in that Jas-Ot is working on for me; I have several of the TCSS thumb screws on hand.
I can't say for sure since I don't have one, but it looks like the Jade pommel would vent sound just fine. You'd just need to have something in place to act as an "echo chamber" (snap ring / c-clip to hold it in place, or a piece of blade stock as a spacer). If the speaker is pressed right up against it, it won't sound as good. Putting a Graflex pommel onto a coupler for my ASP caused the PnP kit to just fall against it; there was a lot of buzzing from the bass speaker hitting the pommel.