And a PG13 rating would help them understand the complicated political machinations and faction hierarchies which are difficult enough for adults to follow?
This is a show aimed at adults I see no reason to neuter the content to make it palatable to kids when the structure of the story isn't designed for them anyway. It's not a kids fantasy show any more than Deadwood was a kids western.
Frankly the show should be more depraved and vile. Medieval settings are always glossed over and romanticized and even Thrones makes living in a world of that era seem more palatable than it should be.