I started this google group because there seemed to be no channel for communications with the developers but forgot it was even out there until you wrote. SpatialKit has always seemed like a side project for the developer(s) but they usually respond pretty quickly when messages were posted here.
Opening the source would be great, wouldn't it? Seems unlikely all the same. Even though it's appears to be a low level project they release updates periodically.... though the latest is for 10.2 which makes it about 3 years out of sync.