Manager had nothing to do with projects success since he's just been hired out for marketing purposes but i can say that he do somewhat contribute because this is how marketing works
to give out exposure.
If it did succeed then lucky for both manager and its advertisers.
I agree with what you said about the managers having contribution. Whenever a good manager gets hired to manage a bounty or signature campaign sometimes that feeling of doubt in joining the campaign can be quickly removed but once things go bad it's collateral damage.
sometimes we cannot put too much pressure on bounty managers because he is not part of the project team and indeed many bounty hunters now blame the bounty managers against the project he manages because it ends in fraud.
It's true that we can't stop bounty managers from their decision but we can still do something about it like simply avoiding it even though it looks like a legit campaign. Or start a thread in the reputation section to discourage these behaviors.