I say you are not justified in that swarms are just as much anyone's as they are yours. place your own traps or manage the bees so they do not swarm. that is your best recourse. You have the upper hand in that you can make artificial swarms when you see it is necessary. all the others can do is hope you mess up. If you do those where lost bees to you anyway. at best someone else gets them and starts a hive out of them. IF you have traps in place you have just as much chance of capturing your own swarms as they do. but a swarm is an unowned item.
I understand that you don't like it, that dos not make it wrong. and placing traps has nothing to do with weather your hives swarm. Your management of them does. You have the opportunity to make their efforts fruitless.
Everything gets darker, as it goes to where there is less light. Darrel Tank (5PM drawing instructor)