And? That's supposed to what? Make me happy? That he appeared in Rebels is annoying. That people are demanding him makes him frustrating and will lead to further disappointment down the road.
In my humble opinion. Loose end that needs tying up doesn't make it good.
I'm not looking forward to Thrawn in "Ahsoka". If he does appear in it, I hope he's finally bumped off. I don't like Mary Sues and Gary Stus, but I like villainous versions of these tropes even less.