Yes, his number should be retired.
and - Un-retire numbers? Really? who do you think doesn't belong and why? http://www.nba.com/celtics/history/RetiredNumbers.html
I mean the one that seemed most unworthy to me, at first glance, was Max, but...7 years, 2 titles and a Finals MVP really kind of make a compelling argument. He told them "Jump on my back, boys" and delivered.
Interestingly enough, Max is also an argument that would support the idea of retiring Ray's number. For the record, I wouldn't retire Ray's number, but Max was also a key contributor whose departure involved some bad blood.
Brown and Red shouldn't have numbers. I have no issue with their names being in the rafters, but they shouldn't have numbers associated with them.
If I was doing this I think you could at least make solid arguments that the following people should not have their number retired (in order by number): Dennis Johnson, JoJo White, Tom Heinsohn, Tom Sanders, Don Nelson, Ed Macauley, Frank Ramsey, KC Jones, Cedric Maxwell, and Jim Loscutoff. And as I said I think you could at least make a solid argument not that they should all be out or that they are all on the same level.
And for the record that would leave these 10 players still in the rafters: Bill Russell, Bob Cousey, John Havlicek, Dave Cowens, Bill Sharman, Sam Jones, Kevin McHale, Larry Bird, Reggie Lewis, and Robert Parish.
There are just too many numbers up there cheapening it for the players that truly deserve it.