Basically this is a "we have nothing to announce at this time". He could also just have said, "no". But i guess that's what his facial expressions were saying, lol. If the game was set to be announced at E3, with all sorts of NDA's in place, do you think he would say "yes, it's coming. Nintendo were supposed to announce it at E3, but since you asked nicely, i'm happy to blow their E3 for them."This is not happening. CEO of CD Projekt RED during today's conference for investors was asked whether any Witcher related game is coming to Nintendo Switch and he replied that Switch is a huge success that they are aware of and if any Witcher game would ever come to Switch they would announce it. I know that this does not seem like he has completely debunked the news but his facial expressions and all that didn't really suggest that something is happening currently.
Link to interview with Adam Kicinski (CEO of CDPR) in Polish. I could translate it but I don't have time at the moment.
This is a bog standard answer, that means nothing. It doesn't mean it's coming, it doesn't mean it's not coming. He's being polite, and doesn't want to blow up any bridges with Nintendo, in case the game is not coming, not to endanger possible future colaboration. If the game is coming, he's simply saying "now" is not the time to talk about it.