Let them do it once without protest and they will surely do it again and again - personal freedom comes with personal responsibilities, one of which is respect for others.
Personal freedom also comes at a cost.
If someone wants to take on risk, that really is their business if it affects no one else.
That is more challenging in regulated and structured environments like aviation.
I don't know what is commonplace in the US, if people leaping out of every Robbie (or any other make for that matter) is the norm, that is y'all business.
In less civilised parts of the world you need training, approval or permissions to lob anything out of an aircraft.
That isn't because of the nanny state, it is because time has shown that with impromptu, dicking-about in an aircraft, eventually someone gets hurt.
Personally I consider good airmanship to be a bit more than if something is legal, or not. A poor choice of location and wobbly correction of a sudden change in lateral CoG doesn't help change that view.
This isn't a video that will help improve the reputation of Robbie drivers, no matter how much one does protest.