The TSA has officially weighed in on this questions with a very clear, “probably not.”
Thanks for checking. We advise packing your ruck plates in your checked bag. Safe travels!
— AskTSA (@AskTSA) August 12, 2016
While this isn’t a definitive “no,” it does support the general consensus of the GORUCK population that even if you get 1 TSA agent that lets it slide, the odd are that the next one will not.
So, best bet is to either toss it in your checked bag, or just go get some bricks or use random weights whenever you arrive at your destination.