Why does Dan Henderson think Rashad Evans should wait one more fight before getting a title shot?

Because the way he sees it, the biggest fight Ultimate Fighting Championship (UFC) can promote is a light heavyweight title unification bout. In other words, Strikeforce 205-pound champion Dan Henderson taking on the winner of Jon Jones vs. Quinton Jackson.
Nothing personal 'Shad, just business.
"Hendo," who turns 41 later this month, laid waste to the Strikeforce light heavyweight division before packing on a few pounds and abrogating Fedor Emelianenko at last month's (July 30) Showtime event in Hoffman Estates, Illinois.

In fact, the former PRIDE champion is 6-1 over the past three years, his only blemish caused by a middleweight mugging from Jake Shields in early 2010 -- one that saw Henderson struggle with his 185-pound weight cut.
He's ready to "make some money" with the UFC by unifying the UFC and Strikeforce titles, even if it means benching Evans in the process.

"I’m ready to fight, and I think I’m a valuable asset to make some money with also, and they know that. I’d like to try and fight in December," Henderson told MMA Weekly Radio. "Take another month off or so and get back to training. It will probably come down to money, but it’s coming from the same people, so it’s a matter of where they’re going to make the most money off of me as well, and to be able to pay what I’m getting paid, they need to be making money as well. I think the biggest fight they could promote is probably a title unification with whoever is the champ in the UFC. I think for them to utilize the best potential to make money for everybody, I think they’d have to have Rashad wait it out one more fight."
There's only one problem.
Aside from the fact that he still hasn't come to terms with his former boss on a new contract, UFC President Dana White isn't too keen on the idea of letting "Hollywood" just walk right into his light heavyweight division and contest for the title right away.
And they've been down this road before.

After back-to-back title losses to Quinton Jackson and Anderson Silva in his 2007 return to the UFC, Henderson reeled off three consecutive wins, including a thunderous knockout over Michael Bisping to secure what many believed to be another 185-pound title shot.

It never came.

That's because his contract had expired shortly after "The Count" did and the two sides had very different ideas as to what "Hendo's" value was.

Henderson bolted for San Jose and may, at long last, come full circle after a stellar 3-1 run with Strikeforce.

That's if they can make the numbers work and if "Dangerous" Dan is willing to accept the fact that he'll have to beat a top contender in the tough 205-pound weight class before getting another crack at the division crown.