Well it wouldn't be arbitrary would it, it wouldn't be 'cancelled', planned ahead of time it wouldn't delay anything and the best price I can find for a coach is £400 which is half a tonne of fuel. Even a return coach for the next punters is arguably cheaper than operating a half empty Dash on two sectors.
And let's be honest, there is a bit of a track record to consider.
Now, before you get all hot under the collar, I'm not suggesting that is the reason for the formation departure but your arguments against it are flawed.