It is neither arbitrary nor moving. If one person has power over another in a corporate context, the senior person should not date the junior person.
A pretty simple way to think about it: who in your company would you be afraid to be frank with if you knew it would upset them? Those people shouldn't be allowed to date you. That leaves billions of people for each of you to date, so I'm not seeing a big problem.
Are there edge cases and nuanced situations? Sure. Is that true about any important rule? Sure. E.g., look at your company's conflict of interest policy. For the sake of clarity, a bunch of relatively arbitrary lines will be drawn. But that doesn't produce the same hand-wringing and rushes to the fainting couches that a rule like this does. I'll leave the reason why as an exercise for the reader.
> the senior person should not date the junior person
What if the junior person realllllly wants to date the senior person. And the senior person kinda wouldn't mind giving it a go. Should the junior be reprimanded for their outrageously flirtatious behaviour? Perhaps we should have a committee draft an exhaustive set of rules that unambiguously eliminate this danger.
My concern here is abuse of power, so I would not make any additional rules in this case. If the junior person is bothering the senior person that's unprofessional conduct and so can be dealt with normally. If the senior person isn't bothered, I don't see why it's any business of the company's.
A pretty simple way to think about it: who in your company would you be afraid to be frank with if you knew it would upset them? Those people shouldn't be allowed to date you. That leaves billions of people for each of you to date, so I'm not seeing a big problem.
Are there edge cases and nuanced situations? Sure. Is that true about any important rule? Sure. E.g., look at your company's conflict of interest policy. For the sake of clarity, a bunch of relatively arbitrary lines will be drawn. But that doesn't produce the same hand-wringing and rushes to the fainting couches that a rule like this does. I'll leave the reason why as an exercise for the reader.