Calling the behavior of boaters "stupid" is not how I see it. For one thing you classify them as "boaters". If they were standing on the land would you call them "standers"? They are people and people are curious or perhaps even interested! I do not see how they impeded the recovery effort. The Coast Guard appeared to keep them out of danger to themselves and the recovery crew. They did their job! They just didn't like it.
Regardless of where the splashdowns occur, said splashdowns are made public. Finding out where the splashdown will take place is easy enough to do even if it were not made public information. I suppose if NASA/Space X wanted it to be unattended by onlookers or secret, they might try not even suggesting when/where a splashdown might occur. Huh, imagine that, not having instant media coverage to protect these programs, whoda thunk it? Rocket science?
As far as a risk of being exposed to carcinogenic toxins, perhaps these rocket scientists need to either NOT USE these carcinogens or find a way to eliminate the possibility of them being released (highly unlikely). But I guess if we leave it to rocket scientists to fix these issues we shouldn't hold our breath or perhaps we should! The final frontier is the next phase in places we are going to ruin with our garbage, just like they have within our own solar system. Either way it is a lose/lose endeavor. But name calling is always a solution isn't it?
Some things to think about, science for example. We are curious creatures. We begin by wonder and by examination. We innovate and invent and eventually we explore, we do so at great risk and human sacrifice. Science seems to have disproved the theory of creationism and the theory of evolution has determined that the earth was here long before "human" life.
In the few thousand years we have existed, even with all of our great discoveries, still we have thick and empty heads. We are going to colonize other orbs? Or at least we think we are going to. Some think that human life is going to exist forever so we are going to explore the universe. This is laughable at best.
What we are doing is interrupting, if ever so minutely the natural evolution of the universe with our toxins and poisons and space junk. What we are doing is getting in our own way. We are literally standing on our own neckties and trying to stand up at the same time. In this position, bent over, we are eventually going to "get it" in the end!
But no really, name-calling is always the right thing to do!