I've given this a good bit of thought; I'm sure its easy to generate plausible deniability, but actually masking relationships is not as simple as it sounds, as

I've given this a good bit of thought; I'm sure its easy to generate plausible deniability, but actually masking relationships is not as simple as it sounds, as an adversary will easily filter out random noise. You would need chaff deliberately constructed to look a bit like non-random social network/communication data; that's kind of a research project, and its going to be hard to guarantee it is working in the face of unknown statistical attack.