That history is not quite right.
When the Spurs traded Scola in the summer of 2007, they had a plan. The plan failed, but there was a plan. They brought back the whole squad that won a ring in 2007 for one more try in 2008. They signed their 2005 first round pick, Mahinmi, with the intention of training him in Austin for the entire season and having him ready to join the big team in 2008-09. Their 2007 first round pick, Splitter, was expected to play out his contract in Spain and also join the team for the start of 2008-09 season.
Then lots of things went wrong. After playing the 07-08 season in Austin as planned, Mahinmi had a mysterious ankle ailment that defied proper diagnosis for months, eventually requiring surgery and costing him and the Spurs Year 2 of his rookie contract. Meanwhile, Splitter's sister had a cancer that recurred and eventually took her life, which led him to take a much more lucrative deal and remain in Spain until he was no longer bound by the rookie scale. So Splitter didn't arrive until 2010.
When the 2009-10 training camp began, Ian was starting Year 3 of his rookie contract and the Spurs had to decide whether or not to pick up his 4th year option by the end of camp. They had drafted DeJuan Blair in the 2009 draft and the simple truth is that Blair outplayed Mahinmi over the course of that camp. If the play-by-plays of those games still exist, I'm certain they'll show that Ian was ahead of Blair in the rotation the early games, but was outplayed and moved down in the rotation. When training camp ended, the Spurs declined to exercise Ian's Year 4 option and he was a lame duck for the 2009-10 season and played less than 200 minutes. He was an unrestricted free agent in the summer of 2010 and signed a 2 year minimum deal to take his chances with a new team in Dallas.