"With an uncertain prospect of conviction, investigators chose a path that would allow Mr. Wright to remain an “unindicted co-conspirator,” because they deemed Mr. Duffy, a sitting senator, to be of greater public interest than an unelected senior official in the Prime Minister’s Office."

Well, that's an interesting call — and one that contains clear political implications that should have been apparent at the time. 

First off, why, when our interest is in abuse of power, is a common or garden sitting senator of greater public interest than questions concerning the conduct of the most powerful public servant in the land?

Second, Duffy's case centred on the argument that he was being set up by the PMO — an argument that the court essentially accepted. In that light, the RCMP's decision could be seen as as clearly prejudiced against Duffy.