> I'd certainly expect visitors to be held to the same standards as the natives.
Visitors are held to a higher standard than natives. Visitors do not have control, a vote, etc: they are temporarily permitted by the privilege of policy at the time.
> as a US citizen I don't want to be respectful and quiet, especially when I disagree with my government.
Good, don't be! You're not at risk of having a visa revoked or go unissued.