I think you are overreacting yourself a bit.

Porn is rated for some reason to 18 and above. As a commercial airplane is public space with repsect to that, there is a problem in playing a pron movie on board, especially as minors are on board. Obvisouly they were aware that wathing such a movie in public is not accepted by the broad majority (thus unlawful), and tried to hide it.

Actually I think they reacted great in trying to conceal the situation, and for that I think they deserve a thank you, but in the end they played the game, were caught and were stoped doing so.

There is a fine line between free speech and offending others, and here it was crossed, as the OP obviously was able to see it with out big effort (BTW any teenager would have done the same thing after realizing they were doing somehting they were ?ashamed? or at least uncomfortable with in public.

BTW I don't think the OP was interfering with the lifestyle of the six guys (or yours) or even judging it, but it was a matter of doing something in public space.