If you're intelligent and privacy conscious, yes. I also think a statistically-relevant alternate scenario exists where a person is deleting things selectively

If you're intelligent and privacy conscious, yes. I also think a statistically-relevant alternate scenario exists where a person is deleting things selectively out of fear of (real or imaginary) ideological persecution. I don't see this legal interpretation by federal prosecutors as discriminating between actively impeding an investigation (obstruction) and controlling what information we retain on the devices we own--especially when that information can be recovered from other places, like browsing history. They were looking to create a case for philosophical sympathies and they found evidence of that in both his statements and direct actions. That would be enough to charge him, and yet they've chosen to specifically juxtapose his internet browsing history (and deletion thereof) with "[causing] the FBI to expend considerable additional resources during its investigation." As you said they either recovered the files directly, or else subpoenaed the ISP, and neither could be said to take "considerable effort." They're saying that because he viewed certain videos and pictures (publicly available) online, he must be a sympathizer. I'm saying, yes he's a sympathizer (and deserves prosecution) but his browsing history online should not be a legally valid justification. Unless you want to sweep up journalists & whistleblowers in the process... Even copyright defendants (thanks to the TPP), if the hypothetical owner of defecatingdwarves.us were to demand criminal charges be brought against a cyberlocker illegally streaming their videos, and you just happened to delete the history entry from your recent visit which the plaintiff decided to treat as "evidence." This case isn't creating a precedent, but it's the first time I have seen federal prosecutors use this rationale and it's concerning. I personally don't think deleting your browsing history alone--even selectively--warrants a potential 20yr federal sentence.