Source Dilemma

I'm having a bit of a dilemma right now over a certain source and whether to use it or not. First of all, the research I'm proposing involves computer-mediated discourse analysis and political discussions in certain forums online. Sound familiar? It's similar to the research conducted by Kushin and Kitchener in their article "Getting political on social network sites", on which I did my peer review assignment (I had picked my topic long before reading these articles). My dilemma is that in reviewing this article and the research conducted, I am aware of all the flaws in the research design and implementation. However, their research would be very useful in order to provide a sort of background and support for the research I'm proposing. But since I have found it to be flawed, is it ill-advised to use this article as a source in my proposal?
In fact, I think it might not be that much of a dilemma after all. Their only similarities are in method employed (which isn't unique to their study) and the general subject area of focus. Also, it might be easier to justify the need for my research if one of the fundamental studies in this area has some serious flaws and biases all the way down from research design to implementation and data analysis. I don't think I really have a choice but to use this study as one of my sources, as long as I acknowledge its' weaknesses and don't repeat them.