I don't disagree that on the surface it looks unreasonable but we have no idea what else was occurring. In the end it's up to the controller to make their own judgement & there will always be situations where "clearance not available" is an appropriate response. i.e. pilots have to plan for it. "Though shalt always issue a clearance" simply isn't possible.
As I keep saying it's no different to encountering weather or any other obstacle en route - you simply avoid it. Seriously, how is this any different?
Last edited by le Pingouin; 24th Jan 2021 at 10:33.