It's a plea for public support. By raising Obama's profile as an oppressor, he hopes to turn public sentiment against the sitting government.

As someone else said, remaining silent lets his opposition control the discourse. You can see this clearly in the frenzy of stories in the media about Snowden's stripper girlfriend and the "IS HE A COMMIE SPY?" headlines. Providing a counterbalance makes it harder for the government propaganda machine to sway public opinion against him and turn him into Just Another Terrorist.