If the accuser create fake accusations, sooner of later anyone will realize the truth in the future since he can't hide the whole thing. Most of casinos will do manual withdraw for large amount money and it's make sense if they need more times than usual, it depends on each casino how long the investigation would end. If it's around 1-2 weeks it's still fine, but if it's need for 3-6 months I think it's sign of scam.
Withdrawal time with 3-6 months I think it doesn't make sense even though it's a big withdrawal but basically, the team will verify manual withdrawals in just a few days at least one week never happens for months, sometimes we see withdrawals are delayed for just 1 week we have seen some of the accusations made even though we know casinos need more time than usual, indeed most people are impatient and always want to be fast in withdrawals but if it is a large amount it must be understood because the casino is already reputable it will do it as quickly as possible.
If the withdrawal exceeds months even I will not trust the casino anymore.