First of all, the article never claims a connection to Aramaic.  Hebrew and Aramaic are about as different as English and Dutch.  They're related, but not the same language.  Second, the idea that Gullah is a "Hebrew creole" is nonsense.  Gullah contains words and grammatical features from several West African languages, but NOT Hebrew.  That said, it is possible that the "ya" in "Kumbaya" is meant as a proper name for God.  Marcus Garvey and others were trying to establish some sort of Black nationalist notion that African peoples are the modern Israelites around the time that Kumbaya was written.  On the other hand, this movement ignored the fact that for centuries, Jews have had a prohibition on pronouncing YHWH, and are no longer even sure how it would be said.  Furthermore, from what I know of Gullah, "kum ba ya" would, in fact, be how one says "come here."