@Jetah This is not about sandbox having rules. Yeah some rules are in TOS like account related stuff, behaviour in general, cheating, advertising, and stuff like that. TOS is not a place to say players that "do not play on every planet with your guild members, even we allow you to do that". WTF? That makes zero sense. If any developer would do a stupid thing like that, I would LMAO and leave.
If developers do not want players to cross-realm then they will do in game restrictions to prevent that kind of behaviour. However, I believe that devs will not do that because they do not want to. I bet they want players to have that oppurtunity to play how they want in as many planets they like and they do not want to make any restrictions there.