I suspect that ruling legally gets wiped off the books by the settlement since the case gets dismissed, no?
Even if the ruling legally remains in place after the settlement, district court rulings are at most persuasive precedent and not binding precedent in future cases, even ones handled by the same court. In the US federal court system, only appellate rulings at either the circuit court of appeals level or the Supreme Court level are binding precedent within their respective jurisdictions.
That ruling does not get wiped off, you're right it is persuasive precedent, and it certainly can be cited in other cases, even if it's non-binding. It will be useful. District court rulings are used all the time as cites in novel applications of law like this.