That I agree, we all want to settle or play on trusted casinos, all casinos want to be reputable but there comes a time that there are fake accusations coming from cheaters, and there are miscommunications also, like a player very impatient to cashout when the support is checking his activity we have to follow casinos we're playing because if there are complaints and they are addressing those issues and they are fair in addressing it.
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.