1. Wallace was going to walk at the end of the year. Portland could either let him do that, or try to get as much for him right now as they can. They did the latter, and they did it well.
2. Wallace, for all his talent, was never going to lead the Blazers anywhere. He had a devil-may-care attitude that rubbed a lot of Portland fans the wrong way. He was also a bad influence on other players, Bonzi Wells being a prime example.
It's easy to look at the trade from a distance, it's quite another to be dealing with Wallace day in and day out, year after year. This was a good trade for Portland, and it had to be done.
I think Kahn's pretty much right on in his assessment, although I would not classify it as "ripping" the deal from Portland's perspective.
It sounds to me like he sees a lot of questions that Portland has to answer in order for this deal to be truly considered a success. I think that's fair, but there were always questions that had to be answered for the franchise to succeed, whether this trade was made or not.