This is a good point and you may well be right. In 2010 I was surprised as anyone as I always thought the LibDems were centre left so it struck me as being bizarre they'd choose a centre right party over another centre left. Their rationale at the time was that the Tories had more seats than Labour so the people wanted Tories more than Labour. I don't think that's what their supporters wanted though but who cares as long as you get to be in power