The demo was made in 2 weeks so that it could be released around the time of the USA dates for BTS' tour. It is highly likely there would be some alterations so that the bad guys to make it less off putting providing they are able to get consent from Bighit.
However, despite the fact that Yoongi has recently had black hair and blue streaks, they are not necessarily using their looks from their most recent come back. Namjoon's hair while purple isn't exactly the same style. I don't believe they're necessarily trying to recreate their looks from their most recent come back especially since its an AU in a dystopian world. It's based off them and their looks so you know who they are but they're not like duplicates. Because I'm pretty certain Jungkook has black hair with blue highlights on purpose. Still if you want to give feedback there is a form on the front page.