I don’t think it’s a matter of reasonable or unreasonable - your feelings are your feelings. I look at these things differently, though, especially if it’s something like TV or film where many people contributed to the creative process.
I think of TV and film - where one work is made by many people - as something like a person whose traits come from many ancestors. Sometimes people have awful ancestors, but that doesn’t make them personally awful, even if you can tell very clearly which ancestor a particular trait is from. I can’t stand my husband’s dad. He’s a serially adulterous, allegedly-recovering alcoholic who doesn’t deserve to be related to my favorite person on the planet. But there are aspects of my husband - hobbies, facial features, even food preferences - that obviously come from his dad, and I don’t look at those aspects and revile them. They’re part of his DNA.
In any adaptation of a work by Neil Gaiman, Gaiman is a big contributor to the adaptation’s DNA. But I don’t think of the work as being Gaiman, and therefore something to automatically reject. I’ve read maybe two books by him, and watched the Coraline movie once, so I don’t have any big emotional investment here. But I’ve gone through this whole process with a beloved film where one of the principal actors turned out to be, though not criminal, pretty unsavory.
Books can be more difficult, because they’ve got one author. (Good Omens exempted, in this case.) But if I previously enjoyed a book, I tend to have the attitude that the morally horrible author doesn’t deserve the power to “take it away” from me. Why do I have to lose something because of someone else’s sins or crimes? I didn’t commit them. The author deserves adverse consequences, not me. I might decide to never buy a new copy of a book so the author doesn’t financially benefit, but I wouldn’t refuse to read it again.
People have different mindsets towards these things, though, and as long as you’re not trying to shame anyone who does still like Gaiman’s work, I don’t think you’re unreasonable.