To go into the journalism issue a little - comics, which is where Gaiman made his name, is a small business that's been in decline for many years. It's very cliquish. Mainstream media barely cover it, and there are I believe two journalists (Heidi MacDonald and Rich Johnston) who make it their full time beat. Both of them are, I would argue, too plugged into the industry's whisper network to make it possible to cover a scandal like this properly.
How the whisper network operates:
People can be cancelled for having the wrong politics. The residual Republican voters in the business were mostly pushed out of Marvel and DC in 2016 and have had to go indie.
People who lack social credit in the business can be cancelled for very minor sexual misdemeanours - like, in one case, having flirted with a woman who wasn't attracted to him at a convention ten years earlier.
People who do have social credit - the right politics, the right identity characteristics, the right friends - can be credibly accused of things like major embezzlement or serious sexual misconduct and have most people turn a blind eye. There was one case of a guy who had been serially copping off with underage girls and the response was "oh yeah, we knew he did that, but he told us he had changed".
Let's also say that, since the death of Stan Lee, Neil Gaiman is probably the most famous living creator in the business. DC still make a lot of money from Sandman reprints. He might have been too big to fail.
I know a bit less about how things work in Gaiman's other main realms of activity, book publishing, movies and TV, but, though they're much bigger businesses, I assume similar incentives apply. Could the BBC's reticence on this have anything to do with all the Gaiman adaptations they've invested in?
So you need outside journalists to take an interest. I know for certain that, though Gaiman might be an extreme example, there are people in comics and book publishing who are quite like him. But they're not people who normies have heard of.
Gaiman is just about recognisable to normies, and that pursuit of fame has been his downfall.