Specifically, this section of Rule 4:
Rule 4. You Must Roleplay
[…]Use a lore-friendly name, and follow the naming conventions for your species. Do not use the names of famous real/fictional people/characters. Naming yourself after pop-culture items, icons, or references is also prohibited. Only clowns can use meme names.[…]
Authorize people to name themselves however they want. Why? because this opens up more opportunities for a different kind of gameplay. Had a couple rounds on MRP where myself and security had an interesting Solid Snake in a box vs patrols play.
The restriction is pointless and restricts roleplay as opposed to enhances it. Especially so when there are already multiple references to various outside media present (the box and one of syndie helmets MGs easter eggs in this case for example).
And while it could be argued that being able to name oneself freely could break immersion … Being named Solid Snake probably does so less than a giant paper fortress filled with stick men and stick dogs, which for some unexplained reason is considered “lore friendly”.