While he did say things that were very true and backed up by a lot of research, he did so in the worst ways he could have said them. The point when emailing or writing to reps and senators is to show them that their constituents oppose or support legislation. Not to intimidate them. This will make all of us look bad and will take that much more to make us seem sane and rational in the eyes of the anti's and those that are on the fence.
Though, I am hearing reports that he may not be responsible for sending the threats. I guess we'll see.