I think the only value of Cooke is that he is an easy way to explain that things are always more complicated. Saying "Omerta is bad" is too simple and doesn't get at the reality of the situation. Saying "dopers are liars" is too simple and doesn't get at reality. Saying "anti-doping talk is just PR" is too simple...
There are a few issues wrapped with Cooke that are inappropriately (I think) being bundled, and some that are inappropriately being segregated. An example of the latter: a poster decried the attacks on his character (that he just wanted attention and his ideas are not valid). In that case, his character does matter, because it is the only basis he's giving us for those ideas is his word and his new persona of anti-doping crusader. He doesn't have any more evidence for anything than we do. On the other hand, to say that he is irrelevant is also not a good stance to take, because a culture of shunning any kind of whistleblowing is another problem.
More so, how often have we seen that an anti-doping stance is really an anti doper stance? To think that Cooke is interested more in the good of the sport than the bad in JV/Danielson would go against the patterns we have seen and are seeing. Betsy and Walsh have shown that they're anti-doping is really anti-lance. I have a problem with that. I have a problem if Cooke's anti-doping is actually just anti-JV and Danielson. Even if I am anti-Lance, JV, Danielson, or whoever, I'm not misconstruing my own attacks on them as being for the greater good. That is dangerous, and the issue at play with Cooke. If that's the case, we have no way of knowing whether his pursuit, and the extra layer he is bringing as "insider", of Danielson/JV is based on anything he actually knows, instead of believes. And that matters.
And regarding his own doping, of course it matters, and of course it doesn't matter. What matters is the truth. If he is speaking the truth about Danielson's Lawyers getting him out of B-sample gate, than it doesn't matter if he doped. But if you accept his dealings with TD as a bigger piece of a new anti-doping mission and an absolute truth, then those beliefs are based on a very shaky foundation if he is an unrepentant doper.
So as a comparison, would we accept Betsy's or Walsh's opinions on anything other than Lance can't be accepted with the same value that they earned with Lance. Because they operated on personal vendetta, even if they used that to find truth, it cannot be accepted that every other perspective they share bears the same truth. It is the same issue with Cooke: is it an anti-doping crusade or personal grudge? I think a bitter grudge, (which can still motivate exposing truth) which is why I'll read his tweets about Danielson, but won't weigh his opinion on anything else as any more than some dude on twitter. Further, if he's a doper, then lock him in the same cell he built for Danielson.
Not a summary, but a parallel idea: Just because he's going against the grain doesn't mean he should be celebrated. He should be celebrated if he's right.