I believe is so the owners can use that channel number at a later date if they want to launch a new channel instead of going to the back of the guide.
I can't remember the channel numbers but if Blaze and +1 are on 80 and 81 they can event use 81 for a similar channel instead of the new channel being far away on 92.
UKTV have done it several times with Dave Ja Vu on 25 using that slot to keep a low EPG number available.