At that point they trespass into an area where the law can step in and hold them accountable for violating other people's rights.
You are right , but I do think WT are treading on thin ice with this one. Essentially the video is a) teaching their kids to be bigoted and b) telling them to go preach that bigotry to their schoolmate with gay parents.
Given that most schools in the US and UK etc aim to create a safe environment for ALL pupils regardless of creed, religion, sexual preference and family background etc a kid going JW sherrif all over school and making fellow pupils feel like shit in the process is likely to cause a shitstorm if said gay parents are inclined to make an issue of it. I don't know where all this would lead but I do know one thing, the JW kid is likely to have another viewpoint vehemently rammed down her throat by the school board . A good thing of course but not from a dub parents point of veiw.