I have to admit I am a Stars fan so my opinion here is already biased, but when you look at the goal there was no definitive proof that the goal should of been disallowed and per the NHL rules, unless there is definitive proof the call on the ice stands.
It is a difficult thing to see if you're a Sabres fan, but Brett Hull's winning goal in Game Six of the 1999 Stanley Cup Finals was indeed a legitimate goal. His two shots were deemed to be one possession, and as a result the goal was legal. While it is easy to argue both sides of the argument, in the end it makes more sense to see that the goal was legal.
Hull clearly had his skate in the goalie's crease when shooting the puck, even though it was on a rebound. Even the NHL recognized its error and changed the rule in the future. It's too bad that it was too late for the Buffalo Sabres, who have not won a Stanley Cup or even made it back to the Finals.
It was based off of a rule that was later rescinded, thus basically saying that the goal itself was not legal. While it was a "goal" at the time, as time passed the NHL realized its mistake and took the rule down, unfortunately a few years too late for the Sabres.