” Besides the utter chilul HaShem, what did he gain in Eretz Yisroel? “
No one is purely a Tsaddik or a Rasha, nor are all of their actions. I would like to believe that this person gained from E”Y, and that one action does not negate it entirely.
“maybe had he looked at my direction I would have told him something.”
I think that if you first made some connection, however small, like engaging in small talk, you might have had a better chance. Even asking about his movie may have reminded him that he in not alone and he can’t hide his actions. Often the yetser hara gets a person when they are out of their element and when they think that no one is watching.
BTW, I am not good at confronting people, so take my words with a grain of salt (and a few more grains of sugar).