I guess you're right. I'm sure it's a metaphor (I just mistakenly said analogy). Again, thanks, Naill, for your kind help.

I’ve never heard ‘empty till’ used to describe one’s lack of enthusiasm for something. It could just be a clever metaphor thought up by the writer. Or maybe it’s a British expression that I don’t know about. In North America, we tend to use ‘the till’ pretty sparingly and prefer to say ‘the cash register’ or simply ‘the register’.