Uhh, Newtonian physics doesn't really apply to black holes very well. You would be hard pressed to conclude ANYTHING about black holes using Newton's laws and equations and end up with the right answer except by accident.
That being said, momentum is conserved, so if there was only a single jet then the "black hole system" minus the jet would have momentum. However, I don't think we've ever seen a single jet black hole.
Also keep in mind we have a rather poor understanding of black holes, and that a lot of information that is stated as "we know X about black holes" is actually "general relativity equations evaluate to X" and has not been observed or verified by data. There's still serious open questions about their physics.
