It's his actual job - to represent and follow the opinion of the people. It's called democracy. And if the opinion of the majority is wrong, then, in this case, so be it.
We have all of these safeguards in place to ensure our leaders neither go off the rails completely, nor simply follow the popular opinion du jour with the predictable disastrous consequences.
If we would do that in the rest of Europe, aid to Greece would have stopped a long time ago.