Bean eating was not equating with sex. It was more with PDAs. For example, smooching. If two men want to smooch on a park bench, that's their right. I would never ask them to stop nor want anyone else to ask them to stop. But I would avert my eyes.; it's not pleasant for me to look at.
On the other hand, if a good-looking hetero couple or a good-looking lesbian couple were smooching on a park bench, I'd probably observe for a moment (not creepily stare, mind you) and enjoy the sight.
It's purely an aesthetic on my part and, as I said, it's my problem, not the couple's problem. But I shouldn't be condemned for that aesthetic, any more than I should be condemned for preferring red heads and brunettes over blondes, or long hair over short, or other physical characteristics that make up my aesthetic sensibilities.