Personally I don't think there should be an issue with spoilers for this community.
I think with the HP issue that the OP mentioned, its because there were a lot of people who hadn't read the final book and who had started reading the series towards the release of the final book.
I think with a tv show that's been off of the air for three years now, and that has been in syndication for those three years, not being able to discuss foreshadowing, themes, etc would be kind of pointless and almost impossible to do.