Wait, "stowaway"? I don't recall any mention of stowaways... was this mentioned in a CS that you accepted instead of me? And if so, could you get me up to speed?
In any case, I'm not sure I see the need to make the two of them roommates, other than the fact that they're both Nul... It seems trivial enough that, if I accept that, then I feel like other people might start to request roommate changes for other things as simple as being the same race, and, well, I feel like that defeats the point of having randomized roommates to begin with.
Besides, it's not like you won't get plenty of chances to interact elsewhere in the RP. o_o If anything, forcing both of those characters to have roommates besides each other just means more interesting interactions in total... since it won't be completely focused on just the two Nul interacting, you know? :P