No? I’m comparing it to something like hugs, which are acceptable cross-gender greetings in some places
No it's not, not among strangers in a random situation like sitting besides each other in a plane.
But sure if both parties are OK with it, why should society be involved with a voluntary legal interaction between 2 people that consent?
Not consenting to sit beside a woman however is CLEARLY discriminatory. As is attacking the flight attendant for doing her job! It is not normal or polite behavior. It is prejudiced religious bigotry.
And anyone behaving like that can fuck right off, and live in a paradise of religious bigotry in some religiously fanatic country.
You are trying to compare crazy with normal. Religious law is based on superstition and delusions. Democracy is based on the pursuit of building a better and fairer society for all.
Democracy is the opposite of being based on religion. If you want to live under laws based on religion, you do not belong or deserve to live in a democracy.