Surely when the studio optioned the rights, they got exclusivity as part of the contract. That is: it doesn't matter if he got "permission": at that point Asimov's estate had no right to grant such a thing.
Surely when the studio optioned the rights, they got exclusivity as part of the contract. That is: it doesn't matter if he got "permission": at that point Asimov's estate had no right to grant such a thing.
IIRC, if the studio didn't record a grant of exclusivity in the Copyright Office, then the Asimov estate's subsequent grant of permission to the student would not have been binding on the student. That is, the studio might have a claim against the Asimov estate for breach of contract, but the estate's grant of permission to the student would still have been valid.
This assumes, of course, that the Asimov estate did indeed grant an exclusive to the studio; that's one of the (probably-many) things we don't know about the situation.