I disagree. I think he has seriously tarnished his legacy. He had the same opportunity as all the great Pride alumni had. He could have done what Henderson, Rampage, shogun and the rest chose to do. He could have tried to fight the best. He didn't . He had a couple freak-shows, fought some has-beens and lost to a Werdum. That's not the resume of an all time great.
You can disagree all you want, that doesn't mean your definition of "legacy" is even remotely accurate.
What he's done in his career as a whole is far greater than 99% of fighters out there. His last few years has not been his best (although he's beaten a a top 10, a top 5, and #2 in the last few years), the same way Liddell's last 2 years was him getting knocked out almost every single fight in the first round, one being a jab against Franklin, and also losing a decison to Jardine.
Using your logic of "legacy", Liddell has one of the worst ones a person can possibly have, which is why your definiton of legacy is ridiculous.
Fedor will be remembered as the greatest HW of all time whose last few years weren't his best. That's how most great fighters end their career.
Cain, Shogun, GSP, Penn, Sheilds, Bas, Wandy, and probably many other great fighters believe Fedor is not only the best HW, but the greatest fighter of all time.
Trust me, Fedor's legacy is perfectly safe.