Feudalism was built on trust.
Honour is all about trust.
Medieval society was heavily dependent on networks of people who knew and trusted each other. Anyone who didn't trust anyone, and made that clear through his actions, would soon find himself shut out of most real power.
Furthermore, regardless of what medieval society was like, BattleMaster is a game about playing with people. We are not particularly interested in making it possible for you to have 100% mathematically provable certainty that a given guild will never, ever be usurped from you by the person who founded it. If you didn't trust him to be the founder, you should have founded it yourself.
Build relationships. Form a real connection with another person. Trust them, and get them to trust you.
