[prewett]

Having been there recently, it definitely would not have been immediately clear to me that there would be a problem. The boardwalk is next to the pools but clearly not in structural danger. The videos show the eruption being basically vertical, so if you aren't directly next to it, it isn't obvious that the ejecta will spread out a little, and that doesn't happen for a couple of seconds. So if you aren't right next to it, it initially doesn't seem unsafe.

Also, you are likely to visit this area before Old Faithful, so the most you will have seen is some steam going up. My visit was the first time I'd ever seen a geyser, so I would have had no idea what to expect, and presumably the boardwalk is in a safe location. If it were unsafe, they wouldn't have built the boardwalk there, right? (And it doesn't seem like anyone was injured, so...)