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.
The history of WP itself enforcing the GP is instructive. More recently, Panasonic Avionics has been sued for $100M due to GPL violations.