Well some journalists like to twist shit into weird directions and mess with the intentions of answers
I also thought the same, but that black fog probably meant that no matter what he said she would twist it and that would somehow damage him
They could probably twist it to something like "Star Actor thinks actor a and/or actor b are difficult to work with" by implying that since the child actor wasn't difficult to work with does that mean the others (as in the adults) were? Scummy journalists don't need a lot to twist harmless quotes especially if a eye-catching headline is all they need.
I don't really see how asking about working with a child actor was a tricky question? He can just say "No, it wasn't difficult at all. She's very mature and talented and I hope to work with her again in the future."