I don't believe that he was "replaced" (he withdrew voluntarily, btw) before the scurrilous facts were revealed. He backed out becuse he knew what they had found and feared its release. .
We have no idea why charges were not filed, particularly regarding the statutory rape of the then 17-yo. She refused to testify in court? Republican prosecutors protect their own? As for the illegal drugs, unless he's caught with them in his possession they can't do much, can they? The entire thing, again, speaks to Gaetz's lack of moral character, and the lack of moral character of those who tried to stop this report from going public, those who defend him, and most of all, the fascist sleaze who wanted him to be his AG... knowing all of this well before we did.