Coming clean in their ANN thread to make it known that it's a KYC casino still won't stop interested users from using their services in as much as they render quality and fair service. Taking gamblers unaware isn't anything encouraging especially with KYC issues.
Well some casino make it a marketing stunt to announce that they are KYC free, so that people get attracted to the casino. Later when they find out that they are being ask for KYC at withdrawal, than they feel annoyed and think that the casino told false at the start. It is always better to play at a honest KYC casino and not at a dishonest casino without KYC. If the casino is very clear in the KYC policy, the gamblers like this transparency and they will still be attracted to the casino.
Showing false advertisements to promote the casino will never be helpful to gain the long term gamblers to the site. People will just come and go once they know the reality.