Two options for VIA right now: 1. No official confirmation about Zynga and long downtrend.
2. Official confirmation and panic buying...
First option 1, then option 2.

why the dev team not to official announce this great news?
Because the dev team had nothing to do with it being disclosed. It was a screenshot from user TechGen.
Also, even if the dev team were contacted by Zynga, it's possible they couldn't disclose it as well. Time will tell.
True. And that guy "TechGen" is gone. His last post was with that "screenshot"...