BYG was operated by Fernand Boruso Jean-Luc Young, and Jean Georgakarokos, and also funded and promoted the Actuel festival of new music in Amougies, Belgium, were connected to the Actuel magazine founded by Claude Delcloo (later run by J-F Bizot) and Current magazine, which was of a more political flavor. Pretty sure the BYG folks stepped out of the publishing biz soon after 1970. Georgakarakos remained involved in music, most notably operating Celluloid (Material, Billy Bang, Golden Palominos, et al.). They were definitely connected to filmmakers and others in French underground media in the 60s and beyond.
I seem to recall that Mobley was more part of that scene than recordings would outlay, and Shepp and Philly Joe Jones would probably have been the connection.