Just ordered a new carb body for my 1 week old 2.5R today. \: Same thing... stripped the HSN out of it. Had no idea the threads were that flimsy. I'll certainly only finger tighten it next time.
My Sirio .18 that recently gave up the good fight had a similar composite carb body, and it never stripped. Not sure what's different about the traxxas one, but it's very fragile. You can pull the HSN completely out of my stripped one with no effort.