If you're referring to Till's sexual assault charges, they were dropped for lack of evidence. That doesn't make him innocent, but neither has he been proven guilty.
Without getting into the "separating the art from the artist" argument because I'm not nearly smart enough to get into the detail, it's still a good song.
The Lostprophets songs like Fake Sound Of Progress and Bring It Down bring me great joy and inspiration when out running, even if Ian Watkins is a colossal cunt.
e: for those new to the story, please do check which Ian Watkins that Google returns :)