I think it’s worth noting that druids aren’t inherently peaceful, they just fight for different causes than most. They fight to preserve the balance of life, nature, the wilds. Their main organisation–the Cenarion Circle–didn’t historically take sides in the faction conflict because it wasn’t considered as relevant to their own objectives.
There is absolutely no requirement of pacifism/peacefulness to enter the Emerald Dream. Thaon Moonclaw from the Val’sharah story during Legion is a good example of this – he’s very much of the opinion that druids need to be on the front-foot, proactive rather than reactive.
Since I’ve answered the latter half of this already, I’ll focus on the former part. Consider it like this: the Horde, under Sylvanas & Saurfang, invaded the heart of night elven civilisation, Ashenvale – a practically sacred forest.
The Horde invades, murdering their people, their friends, their family, basically setting the forest ablaze in their war of aggression. This ends with Teldrassil–one of the World Trees–reduced to cinders, along with all the people who were unable to escape. Setting aside the cost of lives and livelihoods, this was an exact of blatant disregard for the balance of life and the sanctity of nature. The Forsaken were employing Blight by the time of the battle for Darkshore.
Our most recent interaction with Malfurion was in the novel Shadows Rising by Madeleine Roux, where–like Tyrande, Maiev, and Shandris–he’s regrouped at Hyjal, refuses to answer any missives from Anduin (who had signed a peace accord with the Horde) and the four are clear that they’d only consider reparations if they started with the presentation of Sylvanas’ head. Basically, his stance was a continuation of his depiction in BfA.
Now, obviously Tyrande has had a whole character arc during Shadowlands, so there might be some shift in behaviour, but ultimately I don’t see Malfurion representing anything softer than distrust and hostility toward the Horde at present, given that when Thrall meets with the night elves during Shadows Rising, they’re clear to him that Saurfang was guilty too (which, yeah, he absolutely was).
Regarding the Cenarion Circle, I think Yorah is probably on the money. Relative acceptance of tauren and troll druids, particularly those who spent BfA trying to fix the big oopsies in Silithus, but varying perspectives on the rest of the Horde – and none of them nice.
My own druid, during BfA, was very clear in their stance – if the Horde-aligned druids of the Cenarion Circle didn’t immediately condemn the Red Team and aid in its defeat, they were guilty by deliberate choice of association, and therefore enemies of the kaldorei. That was pretty fun, and I don’t think their opinion would have changed over the course of Shadowlands.
