I don't see anything wrong with is going to spring training. He deserves to have some fun and it's physical training that has helped him become the player he is. His ability to slide and keep from taking a hit comes from Baseball.
He played soccer last year to "improve his spatial awareness." Nobody had a problem with that. He takes his team mates to his own summer training where they run in sand, nothing wrong with that.
Let him have his fun, stay in shape, train his body in different aspects, and maybe relax a little.