Acts of evil by "aryans": how can you explain them?

It is well known that there are periodic crises in Buddhism, usually - it seems - involving sexual misconduct. I also know that e.g. Vasubandhu claimed that aryans - even if they could still have sexual desire - were incapable of sexual misconduct. Does that mean that everyone involved in these crises are complete fakes or have retrogressed? Quite famously, an important Tibetan llama was even convicted of child rape : can anyone defend the claim any a "tulku" of this sort is a Buddha behind bars?