If that was true Oda could have written Zoro's reaction and had Nami and co call him out on being dickish. Instead Oda chose to simply avoid the situation entirely. He couldn't write his paragon of honour and loyalty accepting Sanji's actions so he chose that Zoro never finds out about it.
Whatever you think of it, Oda doesn't actually believe Sanji acted in a manner that the character he wrote as embodying a Samurai's sense of loyalty and honour would accept. That's really not reassuring.
I don't know how much Oda himself agrees with the moral principles he gave Zoro, so I'm not going to say that Oda thinks Sanji betrayed the crew. But well, Zoro would think that if he learned of it, and that's good enough for me.
I was actually looking forward to how Oda handled Zoro's reactions to Sanji's actions. There was a lot of speculation on what drama would unfold back then. I'm disappointed (and surprised) that Oda simply chose to bail on it entirely.
In the best case scenario, Zoro learning of Sanji's actions would have caused too much drama that he didn't want to derail the plot to resolve.
I didn't notice either initially. It was
@Bogard that spotted it.