It sounds to me like a lot of the objection is the implication that the only options for those on certain medications are to not use them or to not play altogether. If I were writing such a policy for our chapter I’d do something like the following to make it clear that there are options in between to allow safe participation at the individual’s judgement.
“Alcohol and other recreational drugs are not permitted at Alliance events. If you use medication or have other limitations that might impair your ability to participate safely in certain game activities, we encourage you to work with your chapter staff to find a solution that allows you to participate in a way that is safe for you and for other players. Marshals and other chapter staff always reserve the right to remove someone from combat if they are acting in such a way to endanger their safety or that of their fellow players, for any reason.”
“Alcohol and other recreational drugs are not permitted at Alliance events. If you use medication or have other limitations that might impair your ability to participate safely in certain game activities, we encourage you to work with your chapter staff to find a solution that allows you to participate in a way that is safe for you and for other players. Marshals and other chapter staff always reserve the right to remove someone from combat if they are acting in such a way to endanger their safety or that of their fellow players, for any reason.”