This is a pretty simple guide to ensure that if you (Guild Master) has to go inactive for over 90 days that nobody can overtake guild master status
How long does a guild master have to be inactive?
An active guild member can use the Dethrone button to claim ownership if: The current guild master has been offline for at least 90 consecutive days. Note: The 90-day timer only considers the login activity of the guild master character, not other characters on the same account.
How to stop this from happening?
The inactive time is 90 days however, it will only pass to the top 5 ranks so apparently if the GM demotes everyone and puts everyone lower than the highest 5 ranks, it will never offer the ability to claim ownership.
As long as everyone in the guild is at the lowest ranks, nobody will be given the option to dethrone your GM!
The gamemasters are now entirely hands off with guild leadership issues, even if you can prove, say, that the guild leader died IRL so this is an ideal way to ensure your guild stays in your hands