That's fair, but I'll counter with this: First, just because Rose didn't implicate others doesn't mean others weren't doing it. Donaghy rolling over on others could just be a difference in cultures over the time period in question. Maybe Rose just took the high road and didn't throw others under the bus in attempt to save himself like some a-holes would (i.e. Donaghy).
Second, I'd argue that the difference between a manager doing it vs a ref isn't all that much. In both instances, a guy is getting paid to make the best decision and judgment possible to honor his job description, whatever that job is. And in both cases, that judgment and decision making is now potentially impacted through the possibility of winning and losing with the bookie. Yes, it's different because Donaghy is supposed to be impartial to all teams, and Rose was supposed to be loyal to just one, but if - IF - he ever bet on the Reds to lose, then that difference is thrown out the window completely.
And even if he only bet on the Reds to win, he could still have been betting on run spreads and/or other things where he'd have a financial interest that deviated from that of the best interest of the team where his judgment could have been comprised.