Ok, so let's get this straight.
Putting aside them saving those nice zombies incident aside, why the fuck would they get mad that The Grand Saint, aka the leading figure and role model of many people, is going around saving people free of charge? They said that the reason was to create a 'balance' so that pharmacists and doctors can also get paid. But the thing is, even if its only Safi who can use healing magic to the degree where the person healed doesn't need to go to a doctor of sorts afterwards, who cares? She's only one person; it's not like she is healing people on a city-wide scale every time she visits one.
Now, let's go back to healing magic. Correct me if I'm wrong, but so far the manga hasn't told us how healing magic works right? Does it not only heal the wound but also infection? Will it help someone undergoing cardiac arrest? Does it help if there's a blood clot in the brain/heart? If all it takes to stop a fatal complication is someone strong enough to wave their hands, then of course doctors would get the short end of the stick. If that's the case then why are there even doctors? Perhaps healing magic can't do what I just said, so then doctors would be safe; people will still need their services since healing magic can't do everything. However, seeing how its technology (minus magic technology) so far is comparable to the middle ages, I wouldn't really believe the doctors understanding the intricacies of the human body like what today's medical professionals do.
And finally, why did he even mention pharmacists? I'll assume that pharmacists in this world create or at least sell potions. If that's the case, then they will always be welcomed anywhere they go, because if you don't have access to a healer, I'm certain a healing potion would be more affordable than a magic scroll with some healing spell on it. Not to mention they would also sell potions that deter/cure negative status effects.
TL;DR
Mustache Bishop is an idiot for not understanding that doctors exist because they can do some things healing magic can't, and pharmacists will always be welcomed because not everyone can have someone with healing or detoxification magic if adventuring/exploring.