It's interesting they do stuff like this- it has to be from someone "in the know", which is part of why it's so frustrating that there's so little official word on these guys from Japan .
Still... Japan acknowledges them more than the U.S.A.
It could very easily come down to something stupid. The executives might want to distance themselves from the old lines that aren't considered as successful while the artists very often look to pay homage to the line's past. They could sneak this under the radar without anyone being the wiser. There was a G. I. Joe vs Transformers comic a few years back that snuck a few Battle Beasts in as "Antibodies" protecting Unicron
Only the Gorilla got anything near a close up, and there were only a few panels, but still... someone grew up with them and wanted to pay tribute.
By the way, this also implies that Unicron may have devoured planet beast