IANAL but this argument doesn't seem to be on firm footing due to the extradition laws on the books. Technically I can violate a UK law while in the US and indeed be subject to their jurisdiction.
If a UK person is on US soil and breaks a US law, they will be prosecuted by the US. The US can choose to extradite to the UK, but that's not really relevant.
This further weakens the dishonest posture that tourists are not subject to US law