When I 1st started managing I had used an escr9w by the name of masterP. He did a great job for a month or so and I thought he had a decent reputation.

Needless to say he ended up scamming a few users. I'm not sure the total amount he stole but there was 7-8 btc stolen from me IIRC.

I had taken my proof to the companies and most of them ate the loss. I felt terrible and paid out nearly 2btc from my pocket at the time even though many were saying it was not my responsibility. 

That caused me to start holding funds for campaigns myself.

Now getting to your question, should managers be held responsible? Depends on the situation IMO. This person having 0 reputation should have used an actual escrow as escrow is defined as 3rd party.

In most cases the manager is going to be responsible,  but if said manager can show proof they were hacked(and I mean absolute fucking proof) then there may be some leniency but they'd still have to repay the company somehow.