With regards to the masks, it strikes me as a nonsense you can remove them when having a drink at the arena. Obviously you need to remove a mask to drink, but given booze is usually a big cause of crowd issues at sporting events, let alone likely to result in transmission of spit from the person drinking the pint, then surely, if masks are so essential, drinks should be reserved for the bar area alone?
That way if someone wants a drink they make a choice to drink it in a set area (at their own risk), leaving no excuse not to wear a mask in the main part of the arena. I appreciate not all drinks are alcoholic at sporting events, but even drinking a Coke or a cup of tea at an event sans mask doesn't make any sense when it comes to COVID transmission.
In terms of mask exemption, maybe some kind of big red Devils sticker saying "I'm exempt from wearing a mask" on receipt of a genuine letter of exemption at the gate will assist the stewards. Anyone not wearing a sticker, and not wearing a mask, will be asked to leave the arena if they don't put their mask on. I realise this could all be construed as a bit Star of David on the Jews in Nazi Germany, but in this instance we aren't trying to shame those wearing a sticker, and they will also be saved being confronted by stewards or irate members of the crowd taking it upon themselves to police the wearing of masks.
I personally can't wait until we return to normality, if that ever happens, and I appreciate life is full of risks and would be boring if we listened to everything politicians said was good for us, however in terms of COVID, I'd be happy to sacrifice some freedoms if it results in the arena staying open.