I think it would be pretty expensive to have a dinner with the bishop "come one, come all".
That's a whole different kind of dinner. You'd have to have a potluck, serve something cheap like pancakes or spaghetti, but you'd STILL need quite a commitment in terms of facilities, equipment and manpower to feed 300+ people. Who is going to donate the rent for a hall to eat in? Someone has to prepare/serve, clean up, etc. and someone has to "host the event" and pay for the main supplies (plates, silverware, napkins, cups, beverages, garbage cans, toilet facilities, drink dispensers, coffee pots, tablecloths, condiments, and much more).
Is the Resistance that well-heeled? I doubt it.
Again, this person was way out of line being critical of this gathering.