Go ahead and argue with them if you want, I couldn't care less about the technicalities of the land reform act. Pissing them off is definitely a way to make it easier to run events in future.
Every race that is held in Glentress and Innerleithen (and I'd imagine other FC areas) has the route submitted to the FC for approval 6 weeks prior to the event, no changes allowed after that date (except in exceptional circumstances). The IXS Cup is the perfect example - new trail which must not interfere with other trails (hence many small trail gaps) and had to be closed after each event. The IXS track was properly closed off, logs and branches all the way down it as a deterent (which didn't actually work)