The word "troubling" implies that he would be worried about the situation -- it would cause concern; on the other hand, "troublesome" implies that it is annoying -- it would cause trouble.
This is in line with the fact that the dems, who are very much dependent upon illegal voting to retain their power, would be very much annoyed if the immigration laws were enforced. It is a subtle linguistic matter, but I find it telling.
Good catch. You’d think a so called Constitutional scholar that our esteemed POTUS is declared to be would be more precise. Introductary Constitutional Law is usually very pedantic about that kind of thing. However, his lectures were based on how activists could subvert the COTUS, so following other peoples rules is not his strong suit.