Relly need to ask if those 2 sons were arrogant enough to think they could take over the territory, when everyone knows full well that they were striped if their status, and thus have no funds to pay anyone, or are they just entitled enough to think it is still rightly theirs (like how the first guy tried to order the butler to help him)
I mean ther are not getting the territory back, or any other without doing something major, and if Mitsuha disappears it would cause issues (since if they had bothered to look into her, they would know she is on very friendly terms with both neighbours, who are likely to visit and check in on her, as well basically being the F-ing PRINCESS'S best friend. Not someone you can do things to and it not be noticed.
The first idiot obviously did no research since from his body language he is obviously looking down on her and acting like she is a lesser being, but any research in the capital would say do not mess with her or treat her lightly.