He can let them in with a 2 week quarantine period and then host games with crowds at his huge expensive stadium.Gil can't do anything if McGowan tells him to gagf.
Flying non-WA based clubs into WA is currently incompatible with WA's hard border closure.
If McGowan is fair dinkum and consistent he either can't let them in or needs to rescind the current rules and open the border to all.
I know which one I'd be betting on.
Pack up all the Essendon players with negative tests tomorrow and put them all on a plane directly to a quarantine hotel. If they have to quarantine anyway they may as well do it in Perth.