It mentions in his Wikipedia article that he had money although the source was unknown. The issue with vagrancy throughout history is not the vagrancy itself primarily, but the problems of theft and anti-social behaviors that go with it. Since this person had money, didn't steal, and seemed to mostly leave people alone, they weren't a problem and got an exemption because they were well known.

If only they had thought to make anti social behaviours like theft a crime.