Not sure if that's really all that true. I remember US liberals in general being very pro-Snowden and Wikileaks in the beginning. Hell, even Anon had close to folk hero status for a brief while after the news broke just by the whole digital vigilante thing they had going. It didn't really start going downhill until Assange acted suspicious around the rape charges, because of how closely Snowden, Assange and Wikileaks had become tied in people's minds, but even then many people - including on GAF - still supported him and Wikileaks.
The real turnover, in my opinion, was the election. That's when a lot of liberals started viewing Assange as an outright enemy because of the Hilary leaks. It's made even worse by how a very large subset of people blame the leaks and Russia for the election going the way it did; the general attitude towards leaks seem to have been altered altogether. GAF's collective attitude towards Assange is basically a polar opposite today compared to four years ago and Snowden's reputation has suffered both by proxy, and by the renewed hostility towards Russia among liberals combining with the way Snowden is considered tied to the Russian government.
Tldr, it's a bit more complicated than just patriotism.