Leonel knew that he would likely be the subject of a plot very soon. In fact, he didn't know if this was a scheme or not, although he felt that the potential that it was was just about 10%, likely less.
Rosen carried too important a position in the Suiard family, and though the Morales and Suiards were always at each other's throats, Leonel didn't believe that they were incompetent enough to have a traitor at such a high ranking, nor did he believe that the Suiard family itself was a traitor to the Human Domain.
In all likelihood, this was really just a coincidence. But that didn't mean that the scheme wasn't coming.