Why was WikiLeaks founder suddenly accused?

I can’t understand at all why WikiLeaks founder was suddenly accussed of sexual misconducts.
First of all, US government should find out and accuse the information leakers among US government or Armed Forces. WikiLeaks simply got the leaked information by luck. WikiLeaks as a mere web site has the good right to disclose the information they got.
If US government wants to accuse WikiLeaks because of being against national interests, they can openly accuse WikiLeaks and let them stop disclosing the leaked information. Why don’t they do so?
If US government can’t fing the legal basis to accuse WikiLeaks, this is simply against freedom of speech and the very gag by government. Both US government and European nations which support US doesn’t have the right to claim themselves as the nations of freedom of speech any more. By the way, they can’t blame Chinese government either.
If US government accuse WikiLeaks founder to protect their insiders who actually leaked information, the things will turn out to be worse. If so, it means US government can arbitrarily accuse anybody to protect their own interests. This is so called dictatorship.
Are we Japanese the ally of a gag nation or dictatorship?
If WikiLeaks founder really committed sexual misconducts, why didn’t Sweden notice his misconducts until WikiLeaks start leaking US government information? Why did they found out the misconducts now and suddenly?
In addition, even if WikiLeaks founder is accused and becomes guilty, WikiLeaks web site will continue disclosing their information. Who wins what by accusing WikiLeaks founder? Is that simply for taming ardent patriots in the US? Does US government throw away the freedom of speech for getting the support of conservative Christians?
Please tell me what is the purpose of US government and whether we should trust US government or not.