I don't know if I would consider 2 wires for controlling a solenoid and a throttle position switch a "bus". However, Stihl's scan tool does apparently read data from at ;east one of these wires.
Keep in mind that companies patent a LOT of ideas, a few of which might actually make it into real world products. If you really want to make your head spin just try matching Hewlett Packard patents to a specific inkjet print cartridge!
Yes, there may also be multiple patents on different aspects of the M-tronic system. Keep in mind that M-tronic began as Stihl's "intelligent engine management" I believe first used in an MS280 around 2010 or so.
I used the term BUS because it was the title of their patent.