Do you mean approaching with the JCBT forward, hitting the opponent and following up with Up-B? Or even using the bomb tossed up to hit a tall opponent first, then trapping them in Up-B? If that's the case, why not use Up-Tilt instead? Unless I misunderstand.
What I can say is that if you use your second tip (JCBT Up and Up-B), if your opponent gets launched behind you, they may get hit by the bomb on the way down, which leads to another attack like B-air or Up-Smash. This is similar to my technique of approaching with JCBT Up and grabbing, D-throwing and launching into the bomb for another attack. Though I will try to lab this after my 3DS gets repaired to see how we can consistently launch the opponent back. It's a good mixup, though for some reason I don't see it being easy to run in and Up-B quickly.