Iirc, Gaal had a vision of the future, where the Mule mentioned that Hober Mallow had pierced the side of Empire. She told Salvor about this, and Salvor told Hari in the Vault, and Hari wrote it on the exterior, which told Constant and Polly to seek Hober out. Everything in the timeline with Constant and Hober takes place after this.

It's confusing at first because the audience expects that events are happening simultaneously, but it turns out that the whole Constant plot line is actually a flash forward.

So Hober Mallow's interference in everything is really a predestination paradox stemming from Gaal seeing the future. Without her vision, he never would have met Constant and wouldn't have had any reason to rescue her from Tractor, and thus wouldn't have punched a hole in Empire's aura, so to speak.