i suspect that there's someone high up in niji that just doesn't like selen for some reason. Cock blocking her projects at every opportunity, and that's why she's so brazen enough to publicly say on twitter to reupload her song despite not getting perms properly cleared (i mean, how can the perms not be cleared, when the actual author of the song knows her, has given her perms personally etc).
Selen was prob. going to quit at the first opportunity imho - the termination is probably niji's way of saying "you can't quit, you're fired!".