The legal argument he retweeted about witness tampering is somehow even more Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!) than his comment about trump deserving effective assistance of counsel. So there is that.
I mean, he shitcanned Comey. If your gonna go on a flimsy obstruction charge, that's the best one. Claiming a tweet paraphrasing someone as insignificant as roger stone is federal witness tampering just shows how deranged these people are in their hatred of trump. No legitimate prosecutor would bring that charge or even think about it, because it's so rough ridin' stupid it is more likely sanctionable than colorable.