If it enables them to watch content, period, people will find a way.
The argument is honestly irrelevant. Popcorn time is a UX leap from what was previously possible. There may be another UX leap in the physical device on which the content is played, but you can't ignore the moon landing just because it didn't happen on Mars.
It's a UX leap, certainly, but Napster was not just a UX leap, it was used by lots of regular people. Is PCT? Even within the subset of users that are torrenting movies, what percentage are doing that through PCT vs. downloading them for later?
The argument is honestly irrelevant. Popcorn time is a UX leap from what was previously possible. There may be another UX leap in the physical device on which the content is played, but you can't ignore the moon landing just because it didn't happen on Mars.