[babble-on]

Sounds like it just might have been a prank.

[Enterprise]

That is probably the most likely explanation then. I wonder if they were reacting to the SCOTUS ruling and were doing it as a matter of public satire. The mere holding up of signs should not make the incident something they could be arrested for until an agreement is made to perform the act and some sort of overt action is made in furtherence of the agreement.