The quick answer: No.
Film is an expression of your ideas, and in theory should not be limited to only light, morally and socially accepted behaviors and story elements. Of course, I as a Christian have certain limits and guidelines, as do most people for various reasons, but those are personally held and will vary in every individual.
Now, obviously you're worried about the idea. So, here's a question. What are you trying to convey in the film, and particularly by the bombs being on the people? Would that ultimately benefit the film in conveying the message of the film and in bringing along the story, or would it distract and be a determent toward your ultimate end-goal?
Now, this kind of thing was done in Series 2 of the Flash, (Family of Rouges) and it put the tension and drama at a pretty high level. I can't remember how much they actually showed the explosion, and most of it was hinted at/talked about, yet it still carried a huge impact throughout the story. The 'implanted bomb to control actions' idea was also used in Agents of Shield, and I'm sure many other films/shows. It's not something that should be done flippantly, but if done right, and for the appropriate reasons, it can be very effective.
As to being too horrific, that depends on several things:
A. The tone of the film/Intended audience.
B. The execution of the blowing up.
C. The reactions/consequences of their blowing up.
Film is as much about how you do something as it is about what that something is. I wouldn't be that worried about the actually idea itself. I'd personally give a lot more thought into how to best convey that idea in a way that meshes with the tone of the film and accomplishes what you want in the story.
What is the intended audience? If it's 7-12 year olds, you may wanna think twice, or at least be very careful in the way you convey the idea. If Adults, you could be a lot more blunt and raw in order to convey the full impact of the bombs and what they say about the evil leader dude. Also, going really violent may affect your reputation as a filmmaker, so if you're concerned about keeping a more family-friendly image, you might want to be careful in how you show it.
I say, if that's the story you want to tell, go for it. But carefully think about how you will show the person exploding, how the leader/other followers will react to that, and how it will motive the various characters involved. That's the important bit. The execution of the idea.