In the sense that the US letting up on the poor man is a surprise, yes. But without having polled the pro-Assange crowd it doesn't seem like a special surprise that it was Biden. He's been the name on impressive things before, like ending the Afghanistan war (which at the time had been a political humiliation for the US longer than Assange had).

Supporting transparency and good journalism isn't a partisan issue, and there are going to be good people in any administration. Plus Assange wasn't annoying presidents, he was going after people in the deep state.