Your in a pickle as a provider with that, with asthma you are high risk, thefore if a mask note were written for you and you got covid and had a bad outcome (rare but more likely with asthma, especially if it were asthma which caused a problem with the masks (exceedingly unlikely, even those dependent upon oxygen are able to utilize masks) so if your doc consulted his liability provider (cmpa in Canada) he would be reluctant and told to be so if consulted.
Remember this is all about control, providers that have spoken out (not just about this but other leftist causes have faced action against their professional liscence, it is easy to undersrand why they are reluctant)