Hot Network Questions attract bad answers and bad comments, especially when they're about partisan current events like this one. While that question has one great answer and a few good answers (all of which were posted early on), its also attracting bad answers and lots of bad comments, most of which amounted to "Americans are stupid", which have to be cleaned up creating work for mods and users.
"Protecting" the question doesn't accomplish anything since it requires only a single upvote to overcome, and does nothing about comments.
The value, in my opinion, of HNQ is that it shows off good work and attracts new users. But when it starts attracting unproductive contributors or users whose aim is to ratchet up conflict, mods should be quick to shut it down to try to maintain the relatively low level of partisan conflict (at least compared to the rest of the internet) that allows this site to function.
Obviously, my opinion on this isn't universal, but I'm strongly inclined to trust the moderators to judge when the costs of HNQ outweigh the benefits, especially since doing so doesn't hide anything, it just slows down the firehose of users. While the author of the Meta question you quoted is less inclined to have mods intervene, they also say:
At the same time, I am inclined to trust the site's moderators to use reasonable judgment in exercising their powers.
I see no reason here to doubt their judgement on this decision.