I would like the preface this by letting it be known that I do not really watch Pyro or Maddy's content. I've only started recently watching Pyro's for Vampires SMP and now The Flight SMP. Due to this, some of this information might not be accurate because I am just going off what I have seen spread around and all the screenshots.
I think them having boundaries is very important. If someone were to create art of some kind that directly went against their boundaries and showed it to them purposefully, while knowing it goes against their boundaries, then yes, that person should be blocked. You shouldn't go around actively disrespecting boundaries people have set. Adding on to that, I think their boundaries should be respected.
However, the way the two(more so Pyro as I've mostly seen screenshots from him) went about saying it was not great, to say the least.
I have seen people talking about how Pyro is going to send his people or something like that. Again, I don't necessarily watch his content, so I don't know how accurate this claim is. If he did day that, then that is definitely not something he should have said or condoned in any way at all.
One of his discord announcements states: "If anybody happens to come across people violating my boundaries or frankly, anyone's boundaries, I strongly encourage folks to make an anonymous ticket in this discord". In another announcement, he states he doesn't condone harassment, which he obviously shouldn't. Any sort of harassment towards others, especially in a community filled with minors and young adults, is horrible to do.
In my opinion though, encouraging people to make a ticket and basically reporting the person to Pyro and his mods, will lead to harassment. This was likely not his intention at all, but it is what it will, more likely than not, lead to. More specifically, what it has led to. I have already seen posts of people talking about people coming and harassing them over this, even if the person didn't do anything.
Another concern I've seen others bring up that I think is important is how well will the mods or Pyro himself check the accuracy of the tickets? With this reporting system, people could very easily falsely accuse others and lead people to being wrongfully reported and banned.
Adding on to that point, telling the difference between platonic or romantic artworks. Sometimes an artwork that was made to be interpreted as platonic, can mistakenly be interpreted as romantic. Which will, once again, lead to people being falsely reported and banned.
All in all, both Pyro's and Maddy's boundaries should be respected, but their way of saying it should have been worded much differently.