Well, the editorial of the Sun on that day said:
"That is why the Sun makes no apology for repeating the obvious warning: vote Clegg, keep Brown."
Which has to be one of the worst political predictions in modern times. But just because they made such spectacularly inaccurate predictions doesn't mean that I or I think any politician should seek to somehow prevent them from making those predictions or issuing those warnings to the leaders.
As it happens, to be fair that is exactly what editorials are about. Editorials are about expressing partial opinion, and I would defend the right of the Sun or any other newspaper to express vociferously partial partisan views to my dying breath. They seem to be barking up the wrong tree in this particular instance, but that's their prerogative.