I can't imagine why it could be a problem. It is not a liquid and it is in no way flammable or caustic. I can't for the life of me see why TSA would have cause to question it. And if they did I would think you could explain to them what it is and why you carry it.
However, having said that, I have seen TSA make some bone-headed calls that left me scratching my head!
I am still trying to understand how TSA thought I might hijack the plane with my copper O ring pick, on my return from Coz last year.
The recent story of TSA confiscating a small tool from a group of US soldiers returning to the US from Afganastan, while not objecting to the unit carrying their M16's and squad machine guns (unloaded of course) as carry-on, because the tool was considered dangerous, still has me scratching my head.
Back to the discussion about which tools are most effective for being located at sea:
As I recall from my conversations during my recent Coz trip, with 5 of the folks who had the experience of being adrift for 5 1/2 hours after their boat sank, it was a small mirror more than any other safety tool they had with them, that got them located by the searching boats. Their story really gave me a lot to think about, because we all have the attitude that: "it won't happen to me", until it does.