So i saw on reddit that at the end of the game you leave right away and it will throw off the OverWatch system to where it doesn't send in the demo for your account or something like that. I haven't tried this and i don't know if this works for sure but, the person that posted the thread said that his friend has over 900hrs and has been blatantly hacking and leaving at the end of the game and he has never been overwatched banned.
Again im not sure if this works but if this is true please let me know, and if it is wrong then please let me me know as well!
Just trying to get the word out!
I don't think that's how OW works... That hacker was just not reported enough for OW to respond.