Zack Snyder is not "the movie boss". He tweeted it over a week ago, he did not "just" tweet it. And he did not remotely hint the picture could be "a troll pic", he simply captioned it "cryptic", and since you're one who likes to put inordinate stock in rumors, he's likely referring to those rumors that say the Joker either:
[spoil]cameos in Batman v Superman as having killed Jason Todd in a flashback and/or is in prison at the start of Suicide Squad for that very reason.[/spoil]
No, that the various rumor mongering sites all pick up the same piece of fetid meat and try and feed it to their readers does not lend it credence. It means they all heard the same thing from the same "leaked source", just like we did, and are trying to generate page hits.
Again, to say "oh there's some rumors that say this may not be the REAL Joker", despite the fact that the director of the film himself made it public, is a denial mechanism. It's the same mechanism that causes people to say "I don't like this leaked art of a Pokémon, it's clearly fake for that very reason. See all those pixels?"
Could the design be tweaked slightly? Absolutely. The movie just began principal photography. But again, for better or for worse, that's Jared Leto as the Joker.
