It's unlikely you read the first line of that document and no further.
As for whether they knew of it, it's impossible to prove without asking them, or maybe talking to their attorneys. There is only circumstantial evidence, some of it having to do with timing of events that there is no point in getting in to, since I know it won't make you share that idea. But consider these questions, which you probably have not asked or did not learn enough about those events to ask:
Why did Adam Lanza completely destroy his hard drive? He had a printed poster that had his "body counts and weapons used by mass shooting perpetrators" stuff, so it wasn't to hide that. I think he also had or used another computer, that he didn't bother to destroy. What would someone who expected to kill a bunch of children want to hide? And why did he kill himself despite having plenty of ammunition left?
Think of what you know of James Holmes. He shot up a movie theater, right? Why didn't he shoot some people he encountered as he was walking out (he answered this to a psychologist: it would be kind of personal to shoot someone you could see). How do any theories about why he shot up the theater fit with him rigging his apartment with various explosive and inflammatory substances, set to go off if someone opened the door in response to loud music, but not set to go off from a timer despite he reportedly even had a remote-control trigger as well and obviously was competent enough to be able to set a timer-based initiation?
At the start of the trial for Dzhokhar Tsarnaev, his most famous lawyer, a female, said that, not exact quote, "We know he did it. So why the trial? Because we want to know why." Did we learn why? If so, what was the reason? Does Dzhokhar Tsarnaev's Twitter account provide any reasons why?
Just like superstring theory offers many possible solutions to any theoretical question?
If you think whether certain people knew of the linked idea is relevant or important, then you should focus on the most likely answer, not enumerate all possible ones.
Why is this the most likely answer? Or even an answer you think there is a non-zero percent likelihood of? I don't see any evidence of that. I would think it's relevant and important if I knew of any such evidence, but I don't know of any, and also would probably bet there isn't any.
As for whether they knew of it, it's impossible to prove without asking them, or maybe talking to their attorneys. There is only circumstantial evidence, some of it having to do with timing of events that there is no point in getting in to, since I know it won't make you share that idea. But consider these questions, which you probably have not asked or did not learn enough about those events to ask:
Why did Adam Lanza completely destroy his hard drive? He had a printed poster that had his "body counts and weapons used by mass shooting perpetrators" stuff, so it wasn't to hide that. I think he also had or used another computer, that he didn't bother to destroy. What would someone who expected to kill a bunch of children want to hide? And why did he kill himself despite having plenty of ammunition left?
Think of what you know of James Holmes. He shot up a movie theater, right? Why didn't he shoot some people he encountered as he was walking out (he answered this to a psychologist: it would be kind of personal to shoot someone you could see). How do any theories about why he shot up the theater fit with him rigging his apartment with various explosive and inflammatory substances, set to go off if someone opened the door in response to loud music, but not set to go off from a timer despite he reportedly even had a remote-control trigger as well and obviously was competent enough to be able to set a timer-based initiation?
At the start of the trial for Dzhokhar Tsarnaev, his most famous lawyer, a female, said that, not exact quote, "We know he did it. So why the trial? Because we want to know why." Did we learn why? If so, what was the reason? Does Dzhokhar Tsarnaev's Twitter account provide any reasons why?