It is true. You will have your listing removed if you try to list something as an emissions defeat device. If you try a second time then your account will be banned.

I listed a carb exempt factory performance ecu made by the vehicle manufacturer and it was removed for going against the tos.

Although they do allow universal ecus like mega squirt. I could see performance programmers sneaking through if they avoid specific language. eBay can't know the specifics of every single item that gets listed.