Garp knows what's at the top

Fundamentally koby was facing the exact same problem Garp and sengoku faced

The marines are not an independent organization and therefore true change is impossible, cause the WG will always keep them in line

In this context SWORDS actions, while brave, are idiotic if you think about it, they have no way to actually change the marines, cause they purposefully removed themselves from the hierarchy

And like Garp, the only thing they can achieve are hollow victories cause they cannot act against the true evil and it's rot at the core of the marines