Everytime there is somebody hurt, plus with the whole adventurer hurt from escaping the thorns, supply will get scarce and there is no telling when the supply will be back now that hardly anyone wanna work on that place.Don't tell me he's the only one who gathers herbs. Insane that the supply will go down just because he decided it to.
Furthermore if the merchant and other guilds are stopping selling herbs/potions/goods to adventurer in that town, or band up to selling them on very high price, no way people will do the work.
If things become unbearable/too expensive to live and no way to make a living, people can always move out to other town/city, and this will make a SILENT HILL.
And if that local guild want to extort money for quitting fee from adventurers, they can always walk away in silent, and quit from other town guild branch while telling how the guild fuck up BIG TIME, and HQ will hunt them down once that bad news start to tarnish the reputation.
The guildmaster is smart, yes, but apparently is too stupid to see who he is, nothing but a master of a town guild, not even someone important in main HQ.
Now onto manga, love to see how thorns destroy a normal knife and leather armor easily, but everyone clothes and BOOBS got nothing but light scratches.