If you read WikiLeaks' Twitter posts from September and October, you'll see that they definitely took a side in the election.
Here's a blog post where Assange days Hillary Clinton shouldn't be President: https://wikileaks.org/hillary-war/
https://mobile.twitter.com/HillaryClinton/status/45213072969...
There's nothing wrong with WikiLeaks supporting a candidate in the election. I do think it's wrong to pretend they're neutral or unbiased.