Surely an exemption from a need for licensing is just that. It doesn't mean that the activity which doesn't need to be licensed is legal, if the way that it is exercised offends against other legal requirements, by interfering with the rights of people living next door and so forth.

In the same way an activity that is duly licensed might be illegal, if on any occasion it involves excessive noise and so forth.

The fact that someone has a driving licence doesn't mean they have a right to drive dangerously - and the fact that you don't need a licence to ride a pushbike doesn't make it legal to run down pedestrians with it.