I noticed a ‘Senior Ranking’ for one local player, Alan Piper, on his MSA page.
Senior Ranking 103(T) out of 1612 93.7
I, and other Senior players, have no ‘Senior Ranking’. Why?
Armchair Warrior
Senior list 65 and over I believe. 
If I were active player I would be ranked 77th.
Please see the entry “How do the rankings work?”
If the Senior list is limited to only those 65+ then it would be logical change the age to conform with the age a player can first participate in the US Senior Open.
Armchair Warrior
Oooh, if they changed the age eligibility for the Senior ranking, I would make the list. I can wait. I already have too many reasons to think of my age. 
While there is logic in this idea, the US Senior Open would probably be a much smaller event if players of ages 50-64 couldn’t play.
The nice thing about Senior ranking is you have to do nothing to move up the list.
Only 18 of the 65 players in the 2012 Senior Open, played earlier this month, were 65 or older as of the start of the tournament.
Not quite true. You have to remain alive (at least as far as USCF records are concerned), remain a USCF member and you have to play at least once a year.