It not only can be, but it was https://www.youtube.com/watch?v=ApG1XdI-Dd4 there were a few months when JA didn't give any sign and people on /r/wikileaks started asking if he's still alive, then this video was posted. It's fake.
There was also a livestream in which he supposedly gave a "proof of life" by reading out a bitcoin block hash, among other things.
Do you think that one was faked too?