She probably didn’t mean to friendzone him with that and just wanted to make him feel better and let him know he is important to her. Sure she may not know exactly how she feels about him currently, but she definitely thinks he is important to her so that’s a good thing.
Of course his perception is that he is friendzoned, but like, I don’t see why he would think she would say anything other than that right now? Finding out that she thinks you are an important friend is a good thing….meaning she isn’t just going to tell you to go away.
Anyways, I imagine either the tomboy or Hebikawa will start to make legit moves and Kusunoki will start to think about how she feels, get jealous, and then go on some sort of offensive.