So your child is gunned down and you're worrying about what some random conspiracy guy is saying on Youtube? Clearly if they were offended it's because someone brought it to their attention who wanted to stir up a story. He didn't send anyone to harass the parents come off it.
There would be zero issue if his viewers were not actively harassing the people that Alex James labelled.
But they were and are. Thus you are entirely right to have a problem with the chain all the way to the source. And the platform hosting it.