I do not read any part of that ability as dependent upon removing tokens. It's not a cost that he can fail to pay; it's simply the first of two effects that follow his acquiring a lock.
For the record, I am not firmly on either side of the "zero is/isn't part of all" debate. I am on the side of "unless FFG clarifies Ten Numb, all the relevant precedents say you can't spend tokens for no effect."