The history of WP itself enforcing the GP is instructive. More recently, Panasonic Avionics has been sued for $100M due to GPL violations.
A WordPress-generated website is likely not a derivative work of WordPress source code. (Which is why Affero GPL exists.)
The further specifics depend on GPL version employed.
My reaction was largely to the poster's self-righteous attitude about "theft", which has mapped to many GPL violators I've encountered.