I haven't explored the Druid Grove dialogue in depth, but I do agree that Kagha's "I will murder to protect my flock" doesn't seem appropriate given the scene we're shown as players. What I think is supposed to be implied but is never shown to us are the Druid's dead, which are supposedly numerable. We're told that the refugees aren't unwelcome because they're eating up all the food, but because their arrival has coincided with monster attacks and now goblin raids and that the grove is now under thread. If we saw graves, battle sites, or other signs of the Druid's plight since the refugees' arrival, their susceptibility to Kagha's demagoguing might be more clear.
I think the Druids are also missing a critical presence at the Grove's front gate, which from what we can see is defended entirely by refugees. It's hard to believe that the Druids have been hard pressed to defend their enclave since the tieflings arrived when it's the tieflings that are providing their own defense, even if a great deal of their collective effort is currently focused on the rite of thorns. Even a single Druid manning the gate, who can express to us if asked how much heat the grove has come under since the refugees arrived or how many of his comrades he has lost would change the image of the grove quite a bit.
As a side note: if we saw a Druid among the actual refugees, maybe providing food or water or giving some other sort of support, the argument that the refugees are a strain on the grove's resources would seem a bit more real and less like it was conjured up out of the idea that they are refugees and therefor~ etc.