its the official site. i dont know what they want to do but something like a second ico for sponsors? but for what they want a priv key?
one thought, may be their website / web server is hacked, and hacker cleverly put it there ;-)
let's see what does someone from NEO team has to say for this
This is a giveback program for the ICO buyers. You need to post the private key of the ICO wallet you were using at the time, I'm assuming to prove that you were in control of that address so you can receive the giveback (in NEO or CNY).