There is no reason that I'm aware of for this to be listed as the character's name.
The only "source" I've been able to find of this being the character's name is the Splatoon Wikia, where the band members' names were added by one person, along with their headcanon in broken english, with no source. Even some people there are now saying they don't know where the names come from.
Does anyone know of any other reason to think this is her name? If not, I suggest a change, though I don't know what would be appropriate. "abxy_singer_(splatoon)" maybe?