>violate the US Constitution, US law, international treaties, the trust of US allies
Dude, they are an intelligence agency, what the fuck do you think they do? Except the constitutional violation part, that should be reigned in. Violate treaties and trust? Hello are you that naive? If you want to get all butthurt about US violations, start with the wars in Iraq and Afghanistan, which killed thousand, pissed away trillions, and had us take a dump on the world. That an intel agency is developing exploits - this confuses you?
I'm not sure you'll get that much out of studying the Accumulo source code, honestly. Secure coding practices have been widely knows for decades at this point, and it isn't as if they've got some magic way to call sprintf() securely, that nobody else has figured out.
High performance data storage and retrieval? So basically they are interested in dealing with lots of data? I could have told you that without bothering to look at Accumulo (and I haven't). Where their magic lies isn't in the software, it is the DATA, which they aren't releasing (obviously) and don't want to talk about gathering.
It isn't as if they are giving out do_mitm_attack.a or break_encryption.dll.
>To fix existing weaknesses while also deliberately creating others seems illogical and self defeating to me...
Makes perfect sense to me. Think of the low hanging fruit theory. Fix a weakness that adversaries and script kiddies can find (thus, the weakness has no actual long term value) and create ones that take nation-state levels of effort to get.