Care to cite your reasoning? (Bolding mine.)

Yes, other actors besides TSA have access to baggage areas, including airline and airport employees. (As others have pointed out, TSA has far more knowledge of which bags might have items worth stealing inside, and has contributed to lapses in physical security with the "TSA-approved" lock farce, which bad apples are happy to exploit.) But the fact that TSA is just one of several entities with access to checked baggage doesn't mean that it is "far more likely" that someone other than TSA will rifle bags. It just means that it is at least as likely as the others.

I really would love for you to share your logic with us, and support this assertion you've made. Because I don't see how it follows at all.