Nope we can't say automatically that they are cheaters if they said no on a KYC procedure since there are people that doesn't like to submit any vital information online since maybe they are afraid for their personal security and we can understand that since there's huge risk if we hand it to anyone.
But since a reputable casino ask this then maybe people should consider to trust them or if they really have trust issues and can't really trust those platforms that ask a KYC even if they had long years of good service and reputable in this business then maybe playing in those casino who ask KYC is not for them. Then maybe they should think about to stop participating on any online gambling activities since most likely KYC will be ask there.
Gamblers should accept the reality, the days in which they could gamble and not give away their personal information to casinos are basically over, this makes picking the right casino a key decision as now a dishonest casino will not only cheat you for money, but they could get personal documents which could later be used or sold, and since this is something we do not want to see happen, picking a casino you can trust and that will not break that trust is of the utmost importance.