What is the intended use of the Mantis for the lawful player? On the surface, it seems pretty obviously not for people wanting to be on the right side of the law.
TL;DRFor lawful players the Mantis is meant to stop criminals from escaping by pulling them out of quantum travel or blocking it, acting like security forces, though it can also be used for piracy.
You can definitely use it for piracy. That is one of the uses that it's not really designed for, but it fits that role nicely. But for the lawful player, really the whole point of the QED is to stop players, either by pulling them out of quantum travel or by preventing them from entering quantum travel and quantuming away. So for the lawful player, it's really to stop any players that you may consider a criminal, or that the game has determined are criminals by their criminality stat, and prevent them from escaping, either out to another area or just away from you or away from the particular lawful zone that they happen to be occupying at the time. So you're kind of acting like security forces, or really just a way to hold people in place and make them pay for their crimes.
When I was asking around to a couple other designers working on other systems, I got answers such as: the team working on bounty hunting is excited about the possibilities of a crew of bounty hunters going around with a Mantis and being able to pull criminals out of quantum or keep them from escaping into quantum. And of course, when I talked to Dave Haddock, he mentioned that in the lore, RSI is a major military contractor. RSI is the maker of the Bengal carrier, for instance. So they definitely have their military contracts. And the Mantis is something that would definitely be used by the Advocacy, for instance, in their efforts to police UEE space.
It's the same concept behind the security forces that come and scan you and prevent you from quantum traveling away, and in fact require you to not have your quantum device on while they scan you, or else your criminality stat does rise.
And current marketing for the Mantis in our fiction is towards militias. We've had the UEE militia initiative before. This is just one more thing like that, to provide the ship to militias who are trying to defend outposts that are maybe on the outskirts of UEE space. But there's plenty of lawful uses for the Mantis.