i heard, and then read,  that GPL patches CAN be run in closed source systems running libpd, etc. 

it's just GPL externals that you can't use without sharing the code.  

There seems to be a difference in licensing laws between patches and externals, because externals need to be compiled into the binary, but patches are more like "media" which runs on top of that. 

I wish i could find the posts i read about that again....it did make it quite clear why there is that distinction.