//TC, where did you get the figure 250?//
Easy. The Airbus A380 is certified to carry up to 868 passengers. Most popular configurations seat 600 or thereabouts. Running at half capacity (which no operator will unless they double the fares) means 300 people.
But, put simply, air travel and "social distancing" are mutually exclusive. There is no way the guidance can be complied with. So, you either abandon the guidance or kill the industry (which is already severely damaged). It's as simple as that.
Ditto weddings. You cannot expect people to stay distanced at weddings and they won't. So once again you either outlaw them entirely or just let people get on with it. Fannying about with limiting numbers, limiting activities, etc. just will not work. The country needs to get real and decise what it wants to do.