Gura literally told Casey Edwards to check out Biboo. Casey had no interest in vtubing before Gura introduced him to, therefore Occam's razor is obvious with this one.
>Pebbles told himNope, "you missed something" is not something you say to a stranger. Not to mention that Casey is not that easily influenced.
Despite the fact that Advent ruined the holoEN Minecraft arc by making it Advent-only (thanks to management) and then abandoning it, Gura was still cool with them.
https://youtu.be/sprqi7NjDa4 