Being a cynic, I'm of the opinion that he sees a party he can go for leadership of - Cable is a waste of time and will be replaced soon and he sees an opportunity. Chuka doesn't mind what the party he belongs to is called, as long as he can run it.If Chuka was after power and advancement, then surely he would have bided his time in the Labour party for the Corbyn era to run its course? As wonderful and as enlightened the Libs Dems may be, they are hardly going to be in a position of power any time soon. And I do not think Chuka would ever become a Tory.
It's then only a slight slump to the right from them to the conservatives, at least the remain faction of the Tories, so don't rule out another change if the Lib Dem route doesn't give him what he wants.

). Tory MPs would elect Satan if they thought he’d help them keep their seats.