Have you closely read the responses you already have? If so, have you tried contacting John Heald and what was his response, if any? Have you called / sent any mail to Carnival with the info you asked for and with correspondence addressed to the party you're trying to contact? If you've tried the above and failed, that's about your limit. Most companies will not give out personal info re /employees.
Some lessons are learned the hard way.
I don't know what anyone here could do for you and without divulging why you are wanting to contact him, ( your business--not mine )-- I think most would be leery of doing anything if they could --- but the problem is they can't anyway other than what has been offered up in the other posts.
You have to think about what I originally posted --since your cruise, there's been thousands of faces that came and went-- you were one of those thousands.
Again, not meaning to sound hard or uncaring, just factual.