1095A Allocation

My son was on our ACA Policy but isn't a dependent so we obviously now have to allocate a portion to him (my understanding is it can be zero). 

 

This is where it gets interesting and the reason for my question. He made a LOT less than we did and if we allocate a larger portion to him (using different allocations in TurboTax to see where it shakes out), His Refund goes WAY up but ours only goes down slightly.

 

Is there any reason why we shouldn't just allocate the higher portion to him? Am I missing something that could get me/him in trouble with the IRS? Seems like a no-brainer

 

Thanks