I like the idea of stacked/hum-cancelling "single-coils" too.
But when you look at the different noiseless models from DiMarzio, Kinman, Duncan, Fralin, Fender, Lace, Bill Lawrence etc they've all adopted their own approaches to the problem and - presumably - patented them to some extent (although the basic stack concept is now pretty widely used)
So does Tim invest ££££, and many hours, in R&D to develop a unique BKP approach which may turn out not to be profitable? I suspect not, especially since he hasn't expressed any interest in these types of pickups in the past.