You are quite correct that "the written law trumps a web page," but in this case there is no contradiction between the written law and the web page. Quite simply, "only the passenger retains the key or combination" ... and the TSA agents simply use a special TSA key to bypass the passenger key or combination.
Objectively, this is hard to challenge: the passenger does not share the combination with TSA agents and does not remit the key to TSA agents, or anyone else, right? TSA agents simply have the means to open the TSA lock without them (including cutting them if they so wish). Or do you understand the law as requiring that we use uncuttable locks so that truly only the passenger can unlock the case?
But I know that I will not convince you, and that is quite OK
There is nothing wrong with using non-TSA locks. Hopefully TSA can contact you before boarding if they need to; or hopefully they can cut your locks; and hopefully they will graciously use your spare, ready, open locks inside the case to replace the locks they cut; and your gun case will make it on board. I can see your rationale
As to government agents not being fully up to speed, I too deal with a fair number of them on a quasi daily basis, so I certainly understand your point. It seems to me that showing them the web page of their own agency will be simpler than attempting to give them an education on the Code of Federal Regulations
Good conversation indeed. Let us agree to disagree and I wish you the best on your next trip. Mine will be in July to RSA and I will have 4 big TSA locks on my Pelican
By the way, would you share a copy of your "direct correspondence with TSA where TSA clearly and unambiguously stated TSA locks are not to be used on firearms" ? It could be interesting to follow up with them and ask their comment about their own web page. It seems that getting closure on this issue would benefit the entire AH community...