Last weekend Patri Friedman was donning his Five Fingers while traveling about to present on Seasteading. Having anticipated TSA's security check requirement to remove your shoes, Patri had removed his birthday shoes before going through the metal detector at the security checkpoint. The TSA reaction was as expected — absolute "furor" — the TSA folk were all fascinated by the "foot gloves!"
As chance would have it, the same day I had been traveling to LAX (from ATL) and was donning my fivefinger KSOs. I didn't take them off, not realizing that it was a requirement. The TSA reaction was a bit less cordial (even though they never made me run them through the x-ray machine).
Thus what we have here as far as Five Fingers and TSA regulations is a mixed bag. On the one hand, if you don't take off your VFFs before you go through the airport metal detector, you might end up like me and only get some curious questions, questioning looks, and maybe a few "bad vibes" from the Transportation Security Administration.
Or you could just take them off and be the talk of the TSA. Simply put: there are pros and cons to each approach.