That was the 2009 draft but I remember reading that too. My guess is if they would have had Crabtree rated far above Raji Thompson would have pulled the trigger on Crabtree. Crabtree was probably rated slightly above Raji.
Here’s an interview with Thompson from April 2011: "Obviously if there are what we would perceive as needs, that position might get a little more extra care or we might look at that a little more and maybe re-evaluate things a little bit more," Thompson said. "But at the end of the day, we still believe drafting the best player on the board is the best policy. You don't know what your needs are going to be. You might think you have a need at the end of April, or you may think you have a strong position at the end of April, but you don't know where that's going to be come August 1st, as we found out this season."
http://www.gazettextra.com/news/2011/apr/25/packers-still-have-needs-address/#sthash.nJNNB8qT.dpuf
I remember seeing another interview with him in which he mentions the players on the roster also affect how prospects appear on the draft board - another way of saying need plays a part. There’s plenty of evidence need plays a part in Thompson’s drafts just as it does in every GM’s drafts. IMO Thompson is just more disciplined adhering to his board once its set. And he's more willing to trade down for what he perceives as equal value rather than 'falling in love' with a particular player.