This is an extreme level of sexist discrimination, that goes against fundamental values of a modern democracy.
Well that escalated quickly. More seriously, while the man in the OP is definitely entitled, what he wanted was not inherently sexist. Having strict beliefs about cross-gender contact can lead to sexism, but isn't that in and of itself. Most cultures out there put some limit on what unrelated men and women can do or where they can be together, and those limits can be fairly benign as long as they don't lead people to do things like assault flight attendants.