The problem is not in the enctyption, nor the message - it’s in the unregistered broadcast in itself. It can interfere with some stuff and generally can be suspicious, thats why all amateur radio must be properly registered (the damage can be even bigger if you don’t know what your doing, so it is required to pass a test where I live to register an amateur radio).

So you can brodcast anything you want, but if it’s unregistered, be prepared for consequences