Legal / illegal is the wrong term here because this type of thing is a civil matter.
If you were a volunteer admin and receive a cease and desist notice from an expensive law firm with an army of lawyers representing a client with infinite money, what would you do?
Would you pay your own lawyers out of your own pocket to stand up for your freedoms and rights, or would you just roll over and let someone else take up that fight? Would definitely be the latter for me.