Lavos CAN BFR in that key, but I mostly remember that key BFRing through time (Yes, I know he CAN do it to the Darkness Beyond Time, but he didn't). Usually CT Lavos starts with Rain of Destruction. He did it in 1999, he did it in the battle in Zeal Palace, he does it in his actual fight at the end of the game. He BFR'd the crew through time during the assault on Magus's castle, not to the Darkness Beyond Time.
It's really weird to just say he IMMEDIATELY opens with BFR to the Darkness Beyond Time, when that's generally not what his first move is. Or a move he goes to in general, even if it is at his disposal. The most he'd use that sort of thing for in this key, as far as I can remember, would be to bring himself back and start becoming the Dream Devourer.