Basically, yes. I'm assuming you're on JBA HQ 4, so you need to make your way back to the high security area from the bomb making spot (with the voice locked door) and go through the door across from Enrica's quarters (the same one you went through earlier to reach the surveillance room).
Use the retina scan you got on the locked keypad and head down the elevator. Find your way into the 'clean room' area and then to the final 'bomb room'.
You will have a timer start (10 minutes) for you to make it past 3 red suited guards, up a ladder, get past 4 more guards and Emile before you can attempt the bomb defusal.
I thought it was lame, but you have to hack all three methods before being able to reach the bomb core. Neway, defusing is trickier than building as you have to remove the core before it overheats while also not touching the sides. It basically the same as mine building, just in the reverse.
The best way to control the plunger is by watching the 'target' on the right. Lower/raise the plunger as fast as you can while using the left Jstick to keep it away from the sides. Once you're near the top/bottom it will hesitate so quickly pull/release the trigger all the way to finish (this saves a second or two). Just remember that your speed is variable depending on how far the trigger is depressed/released.
It takes some practice, but once you get the feel of it, it's not that hard.
