Duffy was a politician (albeit an unelected one) and Wright was a staffer.

If your goal is to get publicity the choice is easy, especially since most Canadians had heard of Duffy.

As well, having seen some white collar crime relatively close (some embezzlement at a company I was at) the RCMP makes choices like this all the time...oh yeah, and they weren't successful in the case I knew about nor did they come back to get the other ones they didn't  go after before 

The thought is that the lost once and should cut their losses