He might not be as involved now, but he's been involved with the anime on several occasions before, including two movies and at least one filler arc that I'm aware of (the 6 tails filler arc if I remember correctly). I wouldn't be surprised if Kishi sat down on a cafe one day with the anime writers, had a hot cup of chocolate while giving his opinions/tips on how a Kaguya/Hagoromo/Ashura/Indra filler arc should look like, but nothing more than that I reckon. Maybe passing on a note or two. Then again, he might have given them his full trust at this stage, so who knows.