I don't think it is a question of being forgiven. The people who look back at CBB5 with anger at the way S S was treated are still perfectly capable of attributing blame realistically.
What has happened is that 99% of the population who don't care much about CBB5 judge the four protagonists on other criteria. So Danielle = pretty glamour model. Jade Goody = amusing or irritating manufactured zeleb, according to taste. Jack = weasel. Jo = ex-singer, now living quietly with her dogs. Which when you think about it is EXACTLY where they all were before, except for Danielle's hugely increased public profile.
I agree with all of this. They all basically returned to what they'd done before. Jade's "career" is less successful than it was, and Danielle has a much larger profile, but neither are doing anything that different. Also, the way they both make a living is by being fodder for tabloids and trashy magazines (and stripping off for Nuts etc in Danielle's case). So they are constantly in the public eye.
Jo O'Meara's career was singing, and yes I agree she does have a good voice, but even before CBB5 there was not much interest in her as a solo artist. As the other ex-teenybopper pop group member in that year, "Ian"/H from Steps is the closest comparison. He came out of CBB5 a lot better than Jo did, but since then he hasn't done that much either. I doubt Jo would have made any substantial comeback out of being on the show.