What was there for ANYBODY to be offended about?
Even if the comment had been made in a serious manner, it could only be seen as being helpful advice to hide. It's not as if he was calling the immigration officers over to investigate the guy.
There is not a general way in people that are offended can take action. Only members of 'privileged' groups are allowed to have action taken, and most of that is because those groups are told that they should take offence, and not because they are truly offended.