> The framework for how judges operate, and the framework for contract law is quite different.
Only in that the latter is a proper subset of the former; more relevantly, in US law, explicit licenses (even gratuitous ones) are applied under contract law principles, so the framework for how judges operate with them is the same as for contracts.
> How much we trust such decision thus rest on our believes that judges in general can make a reasonable judgment.
No, it rests on how much we trust that and also trust that the only reasonable judgement based on the vague text is one that we would prefer.