Why the Timberwolves might do this trade
I agree with the general sentiment here that the Wolves would get better offers for KG and probably won't do this trade.
However, I was thinking, if this was a real rumor (even if it doesn't go through), why would the T-Wolves consider this trade?
I think the reason lies with Kevin Mchale and not the Wolves best interest. The Wolves have gotten steadily worse and realistically, Mchale does not have a lot of job security. If they continue to underperform, Mchale could easily be out of a job in the next year or two. So while we are all debating what is in the T-Wolves best long-term interest, Mchale might not feel he has that kind of time.
Dealing Garnett for some young talent and picks (like they could with the Bulls) would mean that the Wolves would likely be rebuilding for another 2-4 years. At which time, Mchale might have made a nice core for another VP/GM. If Mchale wants to make the playoffs this year to save his job, he personally might value obtaining several talented veterans, like Miller and Bonzi, to complement their young players like Banks (assuming they would retain him).