Tree, your brother in law is clearly a nincompoop!  I wonder if he feels the same about female humans.  Is our only purpose to pop out kids for our men???
I prefer to let my hens have a rest.  As a female of my species, and one with endometriosis, I know the toll that female hormones can have on the body.  Of course chickens' reproductive systems are not quite the same as humans', but the winter break is nature's way of letting hens' bodies rest.  I think it's respectful to honour them for the eggs they give us by giving them some annual leave. 
I've read that chooks who don't get a winter break tend to live shorter lives.  That's certainly true of the hybrids created for intensive egg production.