You having an opinion that he isn't worth much over the vet minimum does not make it a fact that he had no other offers and might be out of the league next year. That's all I'm pointing out. I trust Thompson wouldn't pay somebody $4M/year who had zero interest from other teams. I'm sure Raji got offers. I'm guessing some were of the 3y/$9M variety. Considering he was projected to get a pretty good chunk of change before his miserable year, he decided to roll the dice on having a good year and making more next year.
For what it's worth, after Raji signed his contract he said he got offers from 3 or 4 other teams.