He's contracted to the Melbourne Football Club first and foremost. I highly doubt as part of of his ambassador role with Red Bull that it would be part of his deal that he needed to attend every single camp, every single year.
There are thousands of elite athletes all over the world that are red bull ambassadors. Think about their professional schedules, there is no way some are able to travel all across the world to attend a camp. Some simply wouldn't have the time.
And I highly doubt a professional sporting club like Melbourne would cater an event based around one individual. Events aren't organised based around what's best for certain individuals.