What would be weird about that? I would like everyone to youtube Obi-Won vs Jango Episode 2 and watch the fight scene. When it starts Jango does #2 ability of this post. He shoots a few shots while jetpacking away and ITS AWESOME.. Of course Jango's jetpack lets him fly 40 feet in the air for cinematic's sake, but in the game it would be a toned down version.
A jetpack disengage, however, is sorely needed for the Mercenary and would fit very well. Personally, I wouldn't see it as one that has him firing the blasters, that'd be weird. But just a quick jet back to get you out of range, maybe something that breaks targeting - that'd be good.
As you were saying, the damage part of this ability doesn't have to be in the game. It can just be a Jetpack Escape mechanic instead. That'd be fine though a little disappointing to me. Following that train of thought, why would a healer mercenary want to jetpack away AND shoot his enemy? Maybe it would be a good thing, maybe not. Leaves you to think whether or not this should be a talent-ability. All these things need to be considered and thats one of the reasons I posted this.