Please elaborate.
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.