These comics are ridiculously intertwined anyway. I have no doubt that John Barber would have wrote a comic where Bumblebee leaves Earth sometime before 2003, eventually leading into the Movie Prequel comic, and it would have made sense. Just reading the Convergence special, the Defiance and Foundation stories are necessary reading along with the Sector 7 series too, which is directly connected to the Transformers Movie Prequel comic. The Sector 7 notes from John Barber refer to real life events, the ARG alternate universe, and the events of the Ghosts of Yesterday novel. Dude knows what he's doing.
Sentinel Prime and the Ark were transported through space and time and crashed on the moon due to being attracted to the AllSpark's location. The AllSpark was attracted to Earth by the presence of the Star Harvester. From TLK, we know that Unicron resides inside Earth, so maybe that's connected.