Horns of a Dilemma

I'm struggling with an ethical dilemma at the moment. The company that bought my employer and had me canned has arranged for me to perform consulting services. All of us have been brought on as part time consultants. If I were to do a good job as a consultant, I would inform my new client how it could save money and achieve maximum efficiency. This information would, however, if taken to heart, result in one of my former co-workers' being cut loose from his or her consulting contract.

I don't yet know whether the folks at the client company are bigger douchebags than my former colleague, so there is no help there. It is inevitable that the client will become aware of the situation, but I don't know whether they will blame me for not telling them and whether this will have an impact on any career opportunities I might have with them. This may take some time because the client company's personnel are not really able to imagine a scenario in which there is no accountability whatsoever, so they cannot imagine that the selling company tolerated as much useless expense and incompetence as I know that it did.

In either case, I would be betraying someone, either the client or my former colleague. My former colleague made life miserable at work in many ways, but I sort of admired him or her for sticking it to the man by drawing a salary for decades while adding negative value to the organization. That was subversive, but I am pretty sure that he or she didn't know that he or she was being subversive. He or she thought that he or she was indispensable, something that made him or her a source of much amusement and frustration. The new people are just corporate tools, and they appear to be competent. I don't yet know whether they have integrity, but I reckon that their goals and behaviors should be predictable and geared at least ostensibly toward making a profit.

My former colleague would throw me under the bus in a second.

What to do, what to do.