If a peer doesn't respond quickly enough they can be disconnected from and marked as bad. Even if they had good intentions their latency might be too high and it's good to disconnect from them.
Check out this very nice link from a sibling comment: https://ncase.me/trust/. You'll see that an adversarial node either is too adversarial and will be cut off, or still gives just enough to not be cut off but if there are other, more cooperative nodes, they will be favored. Being adversarial doesn't work in the long run.
