People seem to find it terribly hard to find nuance when something awful like this happened. But losing sight of nuance doesn't help in any way. Can he participate? Of course he can. Do you need to cheer for him? Of course not, boo as you please, but you're not helping any one with it.
He was sentenced for his crime, first in England but ultimately he served a sentence according to the Dutch rule of Law, which found him guilty of sexual misconduct of a 12 year old, but not of rape, which in Dutch law is an important distinction. He served his time, he's had his punishment. You're more than free to disagree with the Dutch laws and the sentence that he got accordingly. But it's not up to you. One should be judged by a court, not by the media nor by the public.
I read many people claiming that he has no remorse, quoting all sorts of media coverage. If you think you can judge whether there is remorse based on media coverage you're awfully mistaken. I'm not claiming he has remorse, but obviously he'll respond negatively to journalists, and quotes can easily be taken out of context. English media is renowned for being total assholes with zero interest in nuance.
People do horrible things, and this surely is such a thing, but that shouldn't prevent people from ever participating in society ever again. If we would ban people, make them outcasts forever, that is not helping victims nor prevention in any way. What it will do is increase the taboo, people will refrain from testifying against suspects because even though they want them to be punished, they don't want media and public going after them and ruining the rest of their lifes. Despite it emotionally being very understandable, this type of shortsighted public outrage is very counter productive and people should use their brains before they rage.