Nickius Kids is the Nick Jr. programming block for Nickius.
When VidSG1000 (The Mobian version of Viacom and the main channel's creator) needed an Nickius logo, they had no logo for to be great. They didn't like the new Nick logo, inculding Nick Jr. and other Nick-block-ish channels, Then one worker said "Why not release Nostalgia to the wild?" By that He means: Nickeldon, Nostalgia should be the logo, sir." Since Nostalgia was normally what he liked more than the new, he tried it out.
Why it's a block
No, NO, NO, Not for Nostalgia purposes. An block of an existing channel seems more appropriate to Mobians than subchannels.