If TSA is the same one where the inspector repeatedly asserted "I can't tell if this is empty!" about my mostly-empty but oversized toothpaste tube - this strategy might not work.

"I can't tell if this knife doesn't have a blade!"
And you are not allowed to explain it.

Auto parts stores often have really cheap knives for sale up near the checkout counter. Buy one there and throw it or give it away for the return flight.