Hardly, they are known for opposing the expansion of industrious peoples, *sometimes* violently. They do not protect a "turf" like some kind of youth gang, they guard nature and its balance. The temporary presence of refugees and a bumbling theft attempt committed by a small child are a far cry from, say, a forest being chopped down to make room for a new town.
The specification you are now trying to promote in regards to Silvanus's druids did not at all exist in your earlier post (when you were talking about banishment of outsiders), but that's secondary. Silvanus is characterized as "harsh but fair" and as a distant deity. But that is not the same as the "by any means necessary" attitude you are trying to ascribe to him here. Even in nature, whose impartial fairness Silvanus emulates, the young of animals enjoy "puppy license". While it is perfectly in character for Silvanus to mete out punishment to a child or his approval thereof, it seems very unlikely he would choose death, not for Arabella's crime in any case.
I think you are operating on outdated information here (3.x, from the sounds of it). Druids may draw the power of their spells from different sources, just as clerics or paladins now can. I will concede, however, that this particular circle in all likelihood gets their magic from Silvanus, as a nature deity is still a *possible* source.
Yet, in another novel (Brimstone Angels), Torm himself only takes the magic of his young acolyte away after the latter has misused it at least once, and he does not reverse the results of the previous misuse.
5e does not provide a lot of information on this, except for paladins, but even if I think back, the loss of features and spells is always a consequence of something the character has already done (usually resulting in an alignment shift), which they are then being punished for.
Regardless, I can tell we are getting lost in the minutiae of a sideshow here. In the interest of both of our time:
I think Kagha's actions are excessive and immoral, despite her attempted justifications. You argue that she is justified within the framework of her faith and value system.
We have both argued, presumably, to the best of our knowledge, though both largely without providing sources.
I have said my piece. If you have, agree to disagree and go our merry ways?