No, just buying a ussa membership does not mean you can be subjected to testing. It also doesn't even mean that ussa judging formats will be used. It's just one method for an organizing body to secure insurance.
Events do this type of thing all the time. The WSI used to get sanctioned by the CFSA (Canadian Freestyle Association), it was a way for them to get insurance, and a portion of the registration went towards CFSA membership to cover that insurance. They still operated as they chose to, hired Turpin and the boys to judge the event, etc. You probably didn't care back then because they didn't tell you that it was sanctioned, they just did it internally. You still paid the membership but they just included it within your entry fee.
Last year the Honda Ski Tour had FIS sanctioning, so that the skiercross guys could use those results as World Champs Qualifiers. It doesn't mean that FIS came in and ran the show. Kipp and the MSI crew still handled the event.
And if you don't want to be subjected to "regulations and formats" well,,,, then don't compete. Because any competition involves some type of regulations and event formats, whether it's the X-Games, Olympics, US Open, your local rail jam, whatever.
People are getting bent out of shape for no reason. It's pretty simple, you pay some money to enter an event. Buying a membership is simply a part of the entry fee, and any event has an entry fee.