That link is literally an older report and is a section of the report I linked before. That is the theory from before they tested and found they could not meaningfully guide the dart once in flight and they would need the dart itself to be more steerable (they are not as of unclassified data now). They also have (in the later report) listed missile interception as being a potential future use case that currently they don't have the accuracy for. The issue remains that shooting a projectile into space to hit something not very far away is less then ideal and the project was killed in 2021, only to be brought back now.

From another page on the railgun project: Like the Medieval search for the Holy Grail, the USN's search for a "Super Weapon" ultimately proved to be unsuccessful. In July 2021, the USN cancelled the Railgun development program, citing unresolved problems with barrel life and a low rate of fire. The Navy had spent about $500 million to develop the weapon. Future R&D funding will now go to other weapon systems such as anti-missile lasers.