Scola was claimed on amnesty waivers, which made him ineligible to be traded for a year, a period that ends this off-season.
With Channing Frye returning from heart problems that had him sit out last season, the Suns don't need Scola, especially if they feel like going into the season with tanking on their mind. They may have even claimed him with the intention of trading him.
As a veteran big who can rebound with both a post offense and a midrange jumper and who has experience playing occasionally as a smallball center in Houston, I think he is a good fit for the Celtics and a team coached by Doc Rivers.
I'm not sure if Phoenix is willing to give Scola up since he is relatively cheap and I am not sure the Celtics can offer more than other teams if he is available. Ainge wouldn't (and shouldn't) cough up the Celtics' 2013 first round pick for Scola, but a team picking in the late 20s probably wouldn't have the same qualms about giving up the sort of assets that a cheapskate team like the Suns would prefer.