I see. It's a good idea, one that I had considered a little in PHUR's early development stages, but the problem with utilizing spline guides in Anim8or is that it's not easy to make them by hand. You have to draw out the spline, then rotate and position them perfectly, and then likely have to tweak them. Most cases would require a dozen or so spline guides to get good results. A full-blown shaggy animal would require a hundred or more.
PHUR is for fur. Not long fur, just short fur. Granted, it can be used for a lot of other things, but not for realistic hair. Before I turn PHUR into something with hair capability (using spline guides), I would rather wait for Steve to implement the creation of splines via ASL first. This way I can generate the spline guides automatically and the user only has to tweak them.
Though I said that, I'll add it to the to-do list anyway. It'll require quite a lot of code modifications, so I won't prioritize it over the other things on the list for now.