Interesting. I hadn’t read it that closely until now. Maybe the venting refers to the fact that they presumably left the lens out of the rear tip of the tool (rather than being open or vented on the black side facing away from the camera).
Regarding the switch, I’m not sure I would read too much into the PIH description. Based on descriptions I’ve read, I noticed that they tend to throw industry terms with specific means around for things without necessarily knowing that those mean. I wouldn’t bet much on the person writing that description knowing the difference between a toggle and momentary switch, for example. If you watch how McCoy uses it in the film, it appears to be a momentary push button rigged up somehow—towards the end with the Wittnauer logo. It looks like he has to squeeze it reasonably hard to keep it on, actually, as it flickers off from time to time.