As much as he can get under one's skin, and as much as he can be abrasive, and any number of other things, I trust his opinions on security and crypto.
He's rational to a fault--unfortunately, that means that when facts change he may be left with egg on his face. I don't think there's anything wrong with how he's handled this stuff.
I'm also doing the Matasano crypto challenges and they are pretty priceless, don't know of anywhere else who offers a similar learning experience by breaking stuff, for free even.
I find tptacek's remarks to be enjoyable, generally speaking. In regards to crypto, I value his opinion highly, especially compared to my own novice opinion.
That said, I seldom trust anything I cannot verify. In matter s of crypto, that often means that I accept some things as magically working, and accept that the magic could wear off at any minute. Same thing with CPUs. I know generally how they work, and understand bitwise logic, but for the most part, they're just magic boxes that I've got enough experience with to have an expectation of.
In matters of the government, the fault I find with tptacek's arguments (and I hadn't even realized that it was a thing until this thread, but now I'm caught up) is that I think it is naive to trust the government. The federal government is something that our founding fathers encouraged us to be suspicious of. They specifically prescribed that, in order for our democracy to thrive, that we should be ever vigilant in regards to those we entrust with power.
Assuming good faith on the part of the NSA is naive, whether or not they're acting scandalously. Assuming good faith on the part of any politician is naive.
That isn't to suggest that we should never trust anything the government does, but if there's ever the potential for abuse, we should expect that potential to be abused at some point. If there's a loophole that could be exploited in any way, we should expect that it will be.
This diatribe isn't really directed at this comment, per se, but at your "have to trust __something__" comment, which I completely agree with as a generality. As humans, we routinely put trust into a great deal of people and things all the time, but I disagree that a government, even a pristine, flawless, immaculate government, is deserving of that trust, and it is our duty as citizens to thoroughly distrust it.
He's rational to a fault--unfortunately, that means that when facts change he may be left with egg on his face. I don't think there's anything wrong with how he's handled this stuff.