It is possible to make a penis erect whilst a person sleeps you know. Men get them all the time during dreams naturally (hence why they wake up with them). That proves nothing. He was cleared of the drugging charge, which would've required bodily evidence. It was a court case based on a lie, a badly constructed one at that. Easy to believe due to the situation, but under cross examination all 20+ charges fell apart. You get done if there's evidence beyond reasonable doubt, which can be easy to prove in these kind of cases.
Why would a grown man share a bed with a teenage boy and sleep in the nude? Come on, you are really reaching with that excuse. And there were 14 charges, not 20+