Why wouldn't it? Sleipnope has shown disdain and malice towards the living, masquerading as a nonviolent spirit could bring about an end to its goal... Whatever that is.
Firsl of all, its currently unclear, has it disdain against living at all, or against someone exactly. Let's not forget, that the Sleipnope threats (when it attempted to communicate) were pretty personified. So, it may actually hold a more direct grunge against someone in team for some reasons. After all, ghosts that formed Sleipnope clearly put a lot of efforts in trailing the team. And, considering how pathetic they looked after failed attack -
-
http://www.sssscomic.com/comic.php?page=658 -
(and let's not forget that horror/cute scene when they hide inside the car...
http://www.sssscomic.com/comic.php?page=784 ...generally looking tired and miserable)
- this little journey isn't exactly all fun and relaxations for Sleipnope either. This is hard, resource-draining, determined effort. And Sleipnope is capable of rational thinking, don't forget that. It wouldn't do that, if it haven't got some kind of rational explanation for its action.
masquerading as a nonviolent spirit could bring about an end to its goal... Whatever that is.
Maybe, but for what reason? At the moment, when pastor A appeared, Sleipnope planned to overrun the expedition by a herd of trolls/beasts, and for the Speilnope point of view their chances of survival was pretty low (its plan failed generally because of unforceen consequences like Raynir's runes, and force majeure in therms of Onni intervention). For what reason it may smultaneously start some sort of really complicated long-therm decoy scheme, if the expedition was supposed to be destroyed in near future?