Whats the purpose of the RF output on the Igloo box?

It seems to be a freeview aerial pass thru without adding the igloo signal? 
(FYI - Couldn't spot the igloo channel after a digital and analogue scan)

The reason I am asking is my parents have a Igloo box in lounge and a spare TV in Bedroom.
So rather than a extender / HDMI splitter - i thought i'd look at sending the RF downstairs as I current do with my T-Box

And no- they dont want to pay for a second box.


Cheers