Players make mistakes all the time but the margin for error is a lot smaller for goalkeepers for obvious reasons. The result certainly wasn't his fault but he did make another blatant error which led directly to a goal, and with it being the first goal was a pretty costly one. That's not to say we wouldn't have got fu**ed regardless, like
From what I've seen on the pitch I don't think he's good enough to be our #2, but I can completely understand the club not jumping into the transfer window with 24 hours remaining to sign a goalkeeper the morning after a current keeper has made a mistake. We'd have probably gotten our kecks pulled down for some 2nd rate bum and I think the move would have had a negative effect on the overall squad morale
I don't really buy into the whole "margin for error" thing.
It's a team game, and as I said, with any goal against, it's usually a series of errors. It just so happens that as the player that stands out from the rest (different kit, only one in that position), a 'keepers mistakes are magnified.