At that level, any kind of in-person visit is a sign of mutual good will. Traveling to see someone is an act of respect, and opening your doors to someone honors that person. Not every interaction is zero-sum.
Musk posted news of his visit there by showing a video clip of the pool on the Apple campus. No evidence of the two even meeting in person as peers. I get the sense that if this was a friendly visit there would've been a shot of the two CEOs together. It makes me wonder if he even got into the same room with Cook.
Cook made no mention at all of meeting with the CEO of the fifteenth-largest social network.
