If you are a guest in the Kingdom of Thailand, you must accept that there is an abundance of animals here, with dogs being an integral part of the local environment. If you cannot tolerate the creatures around you, then perhaps Thailand is not the place for you. Animals are woven into the very fabric of life here.
For a visiting Swiss national to report another foreigner who is working to help stray dogs is unacceptable. I hope the dog bite was painful and serves as a lesson. It is likely this individual displayed aggressive or defensive behaviour towards the dog, failing to understand canine psychology. Entering the dog’s territory likely provoked the incident, which should have been resolved amicably.
Next time, stay confined to your villa compound. If you cannot handle the realities of life in Thailand, then perhaps it’s best to remain in your mountain retreat in your own country. You reporting another foreigner is breaking many unwritten rules. next time go holiday somewhere else.