Well, no, it plainly isn't all brexit advocates. Just like it isn't all men who harass and disrespect women, hence the validity of "not all men" responses to feminazi radicals, which I believe you're alluding to. But as you're anti-Brexit that leads one to question whether you're being somehow facetious and believe that it *is* all Brexit advocates and that we're all complicit in threats of murder. But then that'd be silly and you've of course shown yourself to be a paragon of rationality.
With just one hashtag you've created quite the quandary.