Probably all fair points. I'll add another in, Aberdeen have a very substantial minority of their support from the central belt.
I could name half a dozen folk i know from Saltcoats/Ardrossan/Stevenston alone who go to more away games watching Aberdeen than they do at Pittodrie.
I've never known a Hearts or Hibs fan from the same area. I'm pretty sure that's replicated across much of the central belt as when i was at Uni there were two Dons fans in my class and 1 was from Strathaven and one was from Clydebank!
There can't be a semi final at a weekend in the last 40 years where the crowd has been as low. Not a dig, just an observation as we had similar numbers vs Celtic at Hampden in the league cup last year. Admittedly a lot closer but off a lot smaller fan base.