It's fine that this version of the X-Men isn't 'your' X-men. But I just want to point out that the X-Men were never supposed to be the world's greatest superheroes. That's the Avengers.
And for a long time in the 80s/90s because they were the popular team they became the Avengers YET at the same time they tried to continue to push their original mandate which was "To protect mutants in a world that fears and hates them". It's not protect humanity, it's protect MUTANTS. But when you're the most popular superhero team for two decades you get Avengers stories mixed in with your X-Men stories.
What Hickman is writing is an X-Men story, they are protecting their own. But they are not being extremists in this case. When Cyclops formed Utopia, that was an extremist ideology because he wanted mutants to be isolated and created an extermination team of the most powerful mutants as a deterrent to any invaders. Xavier is simply seeking to make a sovereign nation and has even given the other countries gifts to show that he wants cooperation with them. If they live in a world where co-existence is really achievable then humanity would accept those gifts, leave mutants alone and eventually mutants would open their borders to anyone. However the world they live in humans already tried to build a Mother Mold to wipe them out. And DESPITE that happening the X-Men sacrificed a full team to just kill the robot. The majority of the staff (sans whatever guards they sent after M and Wolverine) are still alive after that raid.
So are they the world's greatest heroes? No.
Are they protecting mutants from a world that fears and hates them? Absolutely.