a) Snowden haphazardly leaked our documents because he can't abide mass surveillance. He had to do it and risk everything because of his moral convictions.
b) Snowden repeats Putin's propaganda because his safety is more important than doing the right thing. He can abide things like the invasion of Ukraine or interference in American politics in favor of practical concerns.
(You know it's possible for Snowden to have done something good while also being a shithead, right? I'm saying these shitheads can keep each other company.)