Caryl being a “brother-sister” relationship is not canon.
But this is.
And Daryl being chivalrous for Carol and embarrassing himself is.
And Daryl massaging Carol’s shoulder is.
And Carol joking about screwing around is.
And Daryl nuzzling Carol’s shoulder is.
And Daryl smiling and blushing at Carol like a lovestruck little boy is.
All of this is canon. It happened, and it wasn’t just in our heads. NR can interpret Caryl any way he wants, but it doesn’t change any of this. And it doesn’t change the fact that Carol and Daryl do have chemistry, and they do look at each other in a way that is not brotherly.
Daryl doesn’t look at Rick or Merle like this (let alone nuzzle them). He doesn’t look at any of his other friends like that - only Carol.
And same goes for her. Because the love and adoration is overflowing in both of their eyes. Looks like these are not exchanged between siblings or “just friends”. That is a fact. So NR can keep on saying that Caryl are like siblings; the way they look at each other - the way they are around each other - will keep on proving him wrong.