I like the way he’s doing that. It doesn’t deface the billboard. It’s a form of protest. Other than blocking the intended add for a period of time, it’s not destructive.
They can cut this off of there with little problem.
Of course there will be a cost involved, and possible revenue adjustments ahead.
so I made that one up
How do you know he didn't pay for the space? Many billboard ads are actually vinyl covers, although professional ones aren't all saggy and stuff.