Are Labour incapable of being in a coalition?

This post today on Labour Uncut is very critical of Lib Dem Oldham East and Saddleworth by-election candidate Elwyn Watkins and some comments he made on Newsnight about tuition fees. LU seem to find it hilarious that he could have a view on tuition fees (that they should be ideally abolished) and yet still would have voted in accordance with the coalition agreement had he been an MP.

How can you campaign one way but vote another? How would he have campaigned against himself? Picketing his own office? Shouting at himself? Sending himself furious letters? Distributing leaflets saying “Do not vote for Elwyn Watkins – only the Lib Dems can win here”?

And all the while having to do all this campaigning without trying too hard, in case he convinced himself, and ended up not voting the way he intended.

Now I know this is not a world that we are particularly used to but the reality is that the Lib Dems are in a coalition with another party. So it is perfectly reasonable for Elwyn Watkins to have his views on tuition fees but at the same time to make it clear that he would have supported the government and the coalition agreement. If all Tory and Lib Dem backbenchers went against the agreement all the time the government would collapse. All he is doing is making it clear that he is a supporter of the coalition and the Lib Dem policies (and there are lots of them) that this brings. That doesn't mean he abandons all his views and he is still free to campaign for what he believes, after all the more Lib Dem MPs there are, the bigger the influence. It does however mean that he is willing to compromise to get the politically possible Lib Dem policies to be enacted.

Labour Uncut seem to have real trouble understanding this and it is not just them. I have seen lots of comments, mainly from Labour acvitists which if taken to their logical conclusion effectively rule out Labour from ever being in a coalition. Because many of these comments clearly have a problem with the fundamental principle of compromise. Either you absolutely stick to every pre-election position even when you are in a coalition (and hence it would not last 5 minutes) or you have "betrayed your principles" and "sold out" and made yourself a laughing stock.

If this is the case, and this view seems to be widely held by Labour activists from what I can tell then how could Labour ever be in a coalition?