Nothing surprising there.
As a company, ESPN isn't looking to antagonize Lebron or Cavs fans. The stunt is cute, but money is money and access to Lebron and the Cavs as well as the support of the Cleveland fan base is worth far more money to ESPN than what LeBatard earns them with an extra prank.
As for the SI exclusive, I expect this response is partially because ESPN was completely frozen out of from Lebron's camp during FA.
ESPN banks a lot of its credibility on having access to teams and their players. It's why they rarely rock the boat like with the Knicks' formerly draconian media policies, almost never call out officiating, and tend to toss softball questions at most players.
J.R. Smith: "They were pretty much scoring at will. Especially my guy. I don't know what the hell I was doing on defense."
Raymond Felton : "The play was give the ball to Melo."