1. stinger tapped with female threadsI just checked with Steve Laug, at Reborn Pipes (I also contribute there). He has a few blog entries on the various stingers used, but he too has never seen a stinger pinned to a tenon. Those kind of pins would have to be incrediby small. Even so, with a tenon inner diameter of a few mm's, any pin thru the tenon would be quite an obstruction. (I'd use a micro drill bit from an index as a pin punch to remove it) I'd have to see one broken down to believe this is even possible. I'm confident that the stinger in question is a friction fit.
2. Tubed has male threads that were die cut