As mentioned above, there is no enforcement of any TSO requirement. I've been here ~3 years and no one ever asked if my headset was TSOd. (Mine isn't.)

If you are asking because you're considering whether to buy a headset to use here, I strongly recommend getting a pair of Bose QC35s (used on ebay these are <$200) and adding an aviation microphone to it. There are two companies that sell the add-on microphones: UflyMike and NflightMic. They both cost around $250.

The QC35 is very light, extremely comfortable, has excellent Active Noise Canceling, and recharges by plugging it in to a USB charger. Its battery life is excellent - mine needs charging only once a trip. And when you're not in the flight deck, the QC35 is a great noise canceler - good for phone conversations in airports, and perfect for watching movies when deadheading on mainline.