Also, while I can understand your justification, I don't entirely agree with it.
Okay, I'm a hunter. An evil hunter. And I want these goblins to die. So I... shoot one of them in hopes that the goblins will then decide to fight the PCs? Thinking that the PCs, who are standing there making peaceful talk without any sign of readied weapons, are the people to attack with your full forces is pretty silly, and having them decide to attack the PCs when an arrow flies in and hits a goblin from the forest is, uh, a bit obvious as a railroad.
It'd be another matter if the PCs were asked to wait and walk in the woods while the shaman talks with the other goblin leaders, and then the hunter kills a few goblins and then makes some noise to attract the goblin shaman, who sees the PCs standing over the bodies of dead goblin children. That's a feasible attempt to frame them. But this seems forced. As a player, I'd be wondering why the goblins didn't just put us under guard while sending scouts to deal with the attack, given that the PCs didn't leap out and decapitate people as soon as the first arrow was fired.
Because, really, a single arrow attack as an ambush in these situations is going to result in what in terms of the goblin reaction: "Aha, they were lulling us into a false sense of security before unleashing their barrage of, uh, a single arrow shot from the woods, after cleverly getting everyone else, including their ranged-attack people and defenseless-in-melee-combat wizard people right up into our midst!"