Sorry, I made that edit and it wasn't intended to be quite as forceful as it appears it felt to you.
There is no rule about this, no. I can only offer my reasoning, and see if that seems reasonable to you:
Since English is the language of this Stack, the English editions of games are almost always the authoritative reference. In English editions of D&D, measurements are exclusively in Imperial units such as feet (and rarely, yards and inches). Using the unit that's common to English editions of the game decreases the chance that people writing answers will misunderstand the measurement and answer incorrectly.
That's all I was thinking at the time: the foot is the standard unit in English D&D discussion, so converting to feet eliminates a source of error.
Probably what would have been less forceful an edit, while also adding clarity, would have been for me to just add the distance in feet or even just squares after the distance in metres, so that it said "~50 meters (~150 feet)" or "~50 meters (~30 squares)".
So no, we don't have a policy about this, and the edit was well-meaning but perhaps not ideal. You are very welcome to revert it using the edit history view (click "edited [time] ago") or make a new edit to use both measurements side-by-side, whichever you think would be most useful.