I have never heard of the pools being not allowed on the lido deck.. I have seen pictures of being doing just that!
If you go up to Deck 10 or 11, there is hardly anyone up there anyway, so I don't see it being in the way as long as it's not blocking any walkways, ya know?
Carnival Triumph - Spring Break Cruise - 2005
Carnival Victory - Birthday/Summer Cruise - 2006
Oasis of the Seas - Group Cruise - 2010