I think he was always going to acknowledge it in some way and I think how he did it was, as said, very well done- respectful but gently poking fun- which, let’s face it, I’m quite sure Nanne is more than happy to go along with.
If there is genuinely going to be a Nanne Carpool Karaoke, it needs to happen NOW as her 15 minutes will soon be over, but I don’t see why he wouldn’t do it, even if only for an internet clip rather than something he uses on the show. Good for her.