Law can be enforced on some agreement only on both sides in the same time. If you have some pretensions for the user you must have them equally for that same license holder.
How I understand licence is legit only if both sides exist, there must be Giver and Taker. If there only one side exist act of agreement can not be implemented in any way.
Of course some grate power can enforce by fear what they want (“50 years after the author death” or you will be punished), but this is not legit in any way, it is abuse of power by some greedy people.
I can add, that software piracy exist only when the Giver abuses or ignores needs of the Taker.