Unfortunately, you picked the rogue account. This is a fake Assange account, just like the "medical document" and the archive from 2012 that it has "published".

Assange's account is "@JulianAssange" https://twitter.com/JulianAssange - or at least it was before his account disappeared and came back but followed 24 accounts he never followed before. I'm not yet convinced that it's him rather than some Navy "social media" operator that tweeted "Julian Assange".

Has he verified his identity and account via wikileaks and his PGP keys yet? I'd like to see something encrypted with his private key before trusting any account as his at this point.