The hate stems from fear that he's going to get the job permanently. You only have to look at the propaganda pieces from the local media to see why the fear is so real.
Not just that for me. The southampton game, the constant gushing praise of pardew, the "we don't need any players", little digs about people not understanding his substitutions. Also he's hardly been thrown into it, he was practically begging for the job.
there were pretty huge signs before he got the job what a tit he was. It's clear as day now though, and thankfully everyone can see it.