I noticed this during that time and reported on my observations [1]. I'm glad to see there is a followup inquiry, even if it's over a year later.
The core issue I had back then still seems unclear. When I noticed the oddity, the #DNCLeak hashtag was being hidden / censored (at 3 tweets / sec), and during the same time the pro-democrat hashtag #RNCinCLE was trending strongly (at 12 tweets / min).
In this document, is twitter saying it was simply their spam detection and prevention efforts that caused the #DNCLeak to be hidden (and not any ulterior or political motives)?