I don’t know how far up the disaster scale this goes, but I would consider the Moon tantamount to a natural preserve on Earth and a crash landing there to be a serious accident.
As for the Moon, it'll be fine and we regularly crash spent spacecraft into it. Remember it has nearly the surface area of Asia and is constantly bombarded by (much larger) space rocks for the same reason this spent stage was pulled in, we'd be strained to notice the results of the impact even if given the exact coordinates beforehand and it'd look no more special than the rest of the moon. If our human presence/activities on the Moon has been your concern while an interesting it's still not what The Guardian is talking about anyways and not a defense of their use of the clickbait title.
It's likely that this will be the first time a piece of space hardware unintentionally strikes the Moon. Typically, during interplanetary missions, a rocket's upper stage is sent into a heliocentric orbit, keeping it away from the Earth and its Moon.
For launches of spacecraft intended to orbit the Earth, the best practice is to reserve enough fuel in a rocket's upper stage to return it to Earth's atmosphere, where it will burn up. This is what SpaceX and most Western rocket companies customarily do to help control debris in low Earth orbit. The Moon, of course, has no atmosphere for the stage to burn up in.
[1]: https://arstechnica.com/science/2022/01/an-old-falcon-9-rock...
(The “minimize human disturbance of Moon” bit was indeed my personal thought and not really from either article. To me it’s akin to crashing and abandoning a vehicle in a national park: the park will survive just fine but it’s something we should try to avoid if possible.)
