I have not seen any evidence to say Denver has decided to tank and not push for playoffs. They are still within striking distance and I highly doubt a team with a new coach, with a team that just made the playoffs, would elect to not push for it. While I don't disagree that they should probably tank, most teams don't appear to think that way. They may very well think they are closer by making a few moves (moving Faried who may net them a nice asset) along with getting Gallo healthy (for next year). If that is the case, Wilson is a very good piece to help them make the playoffs which is probably their goal IMO.
With regards to what teams would want Wilson Chandler and could outbid the Spurs? I think there would be a few maybe and it wouldn't just be teams who are contending this year. Teams like CHI who probably feel with Rose coming back and a few other moves they are right back in contention could be buyers. That's more of a holistic view, but specifically I would say at least 3 teams could outbid the Spurs and have a need:
1) ATL: They are making a playoff push even without Horford. They are weaker at SF than anywhere and have a coach who values 3/D. They have a few picks this year that could be better than the Spurs as well.
2) CHI: Not a likely candidate on the surface, but they fit the mold I described above. They are a team that while they appear to be rebuilding have the assets (draft picks, players getting healthy & possible cap space) to get back in the mix quite quickly. They likely didn't want to let Deng go, but he was expensive and it netted them a pick. Wilson would be a good fit for cheaper.
3) Suns: This is the team I would say could easily outbid. They have several nice picks acquired, appear to be headed for the playoffs and could use not only a 3/D SF (their weakest position IMO), but a veteran. Their training staff is great which is good news for Wilson and they could be big time buyers.
There are probably 1 or 2 more, but that is all I could come up with at the moment.