This trigger looks pretty nice - tempted to get it as well. But as configured in the photos, it looks like the mechanism that actually depresses the shutter will interfere with the zoom mechanism on the TG-5. You may be able to reverse how it's mounted, though. I don't own the Sony so I don't know where the zoom mechanism is. Will you have a look when you get it, and please let me know? Thanks!
I got the trigger assembly from Nitescuba - it actually took a whole two months to get here, as they shipped it by PostNL, and it got stuck in the Netherlands for a whole month before getting loaded on a flight to Israel. Fitting it to my housing was a bit of a challenge - the ball mount post base turned out to be too wide to pass between the prongs of the trigger's mounting plate, which was solved by an angle grinder, and the tray handle wasn't tall enough for the trigger lever to reach the housing's shutter button, which was solved by inserting an approximately 1cm spacer between the tray base and the handle. Once mounted, it worked perfectly, allowing me to swim and take photos while holding the camera rig by both handles.