Because "guilty until proven innocent" applies to courts. You can get fired from your job even without evidence that meets a specific legal threshold.

Moreover, he's already been proven to be both unethical enough and stupid enough to cheat on his wife with a foreign agent. That's not the kind of person that the board would want to run a multi-billion dollar company.

> You can get fired from your job even without evidence that meets a specific legal threshold

if your country provides adequate legal protections, no you cannot be

presumption of innocence is general approach that morally must be applied everywhere