Not quite. Cryptocurrency is property in the eyes of the law. It's a "thing" you can transfer ownership of.
What the sovereign citizens do is make up something that serves a purpose closer to that of a check, or money order: a thing that is redeemable for money, but doesn't have value itself.

If you find a Bitcoin (somehow just laying on a note card I guess?), it's the same as finding an expensive watch. You now have a thing you own that you can exchange for legal tender. The previous owner has nothing.

If you find a filled out check on the ground, it's worthless to you because it's not made out to you.
You crumple it up and throw it away, and the owner hasn't lost anything.

It's why the sovcits call them coupons, or promissory notes.