The further over the age limit the more remote it becomes, it has only been in the past few years they allowed it, several years ago when they had an abundance of candidates the rule was hard and fast on age, so much so that if a person was in OCS and had medical hold or was rolled for another reason which would put them over the age limit they would have to redesignate or go home.
It is also important to remember that while NRC "approves" the waiver that is just to be seen at the board, the board itself can still look at the age and say "no".