Long was originally banned for two games on a rough conduct charge after he floored Collingwood hard man Brayden Maynard, sparking wild scenes in last Saturday night's match.
The Suns successfully argued on Tuesday night that the charge should be downgraded from high to medium impact, halving his penalty.
They pointed to Maynard, who was left with bruised ribs after the incident with Long, being able to play out the game and laying six second-half tackles.
Just before Long's impact with Maynard, the Magpie had a confrontation with Bailey Humphrey, who had just kicked a goal before halftime.
"Maynard made himself vulnerable as the antagonist," tribunal chair Timothy Bourke said in the verdict.
"This resulted in the impact appearing to be greater than it was."
Long's confrontation with Maynard sparked a wild melee - 21 players were fined, including Maynard and Long. They all accepted $1000 penalties.
After the halftime siren, Maynard sprinted to Long to continue their spat.
Umpire Nick Brown could see the trouble coming and was standing in front of Long.
As Maynard rushed in, he placed two hands in Brown's back to nudge the umpire out of the way so he could get to Long.
Replays showed Suns stalwart Touk Miller, who was trailing Maynard, also made contact with the umpire.Â
Maynard and Miller were controversially offered $5000 fines for umpire contact, rather than facing suspension or having to front the tribunal.
Earlier on Tuesday night, the Western Bulldogs successfully had Kennedy's one-game ban for forceful front-on contact with Sydney's Caiden Cleary reduced to a $2000 fine.
But Bouke said Kennedy was "fortunate" the impact was downgraded from medium to low, adding the tribunal debated the verdict.
"You only just found yourself in the lower category," Bourke said.
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