From what I've been able to determine, Mvix USA owns the trademark and IP for all the Mvix devices, and Unicorn was their manufacturer / asian distributor. Mvix had a falling out with Unicorn and found a new manufacturer for the Ultio. Now Unicorn is pissed and is trying to spread FUD about Mvix USA to scare people away from it. It's petty and childish, and they don't have a legal leg to stand on.
You can search the USPTO yourself and see who really owns the name "Mvix":
Trademark Electronic Search System (TESS)