I honestly can't believe this isn't stopped by the referee the first time it happens.
Gus and Conor both did it repeatedly in a big fight. There is no set of circumstances where you should be allowed to turn your back and run away from the action.
A good example of exiting with footwork is Dodson -vs- Lineker. John would dart away from big exchanges moving either backwards or latterly, but ALWAYS facing his opponent.
If you turn your back to your opponent while standing and jog away, that is timidity and should be an immediate warning from the official.
How can you have been being timid in a fight where you outstruck your opponent, dropped him or finished him etc?
Turning your back on your opponent is a bad move generally anyways, and actual running is way too energy intensive to be a long term strategy for most fighters, but if you can pull it off why not? This isn't boxing where attacks from behind are banned outright, so your opponent should simply adapt to what's happening.
How about this....the Ref should have penalized nate for throwing slaps and 40% punches, who wants to see a fight stolen like that? To this day conor haters and diaz fanboys claim Nate won that fight because nate threw a bunch of slaps that mostly missed, shit should be banned for the sake of the sport....
Anything but fighters trading full power haymakers in the centre of the octagon with no footwork, head movement, jabs, set ups... etc is timidity....
it's not really for you to decide the specifics, anything can happen in there within a set of rules mainly designed to protect the fighters, You are on dodgy ground there and even then, making the octagon smaller is a better idea if timidity is a concern at all. Otherwise it just isn't.