User blog comment:Omega natsu2/Chapter 372: Breach, Predictions./@comment-24536822-20140215073714/@comment-7418318-20140215091233

How?

We've seen Jackal create a ring of explosions all around Michello's house, even in places to which he had no direct line of sight, which most likely means that he creates the explosions directly at the target (much like Shuda in Rave). So Romeo couldn't put up a shield, since the ability would simply bypass it.

But even if blue fire could counteract Jackal's bomb curse in the first place, it'd be power against power and I'm absolutely sure that Romeo has nowhere near the necessary magic power to go up against Jackal like that.