There is on the one hand what the Author wanted in this case, and what the law is on the other. He may have many reasons for not enforcing his rights to the maximum extent.
He may want to be nice, or have done a deal or any number of reasons. That doesn't mean he can't stop them from using it altogether.
Also he can change his mind down the track.
Whether it is infringing or not is up to many factors in each case, but simply extending it is not going to protect you in every case.
If we want a definitive answer, would have to take this to a court.
Source: studied IP in Law school, but not a professor or anything.
He may want to be nice, or have done a deal or any number of reasons. That doesn't mean he can't stop them from using it altogether.
Also he can change his mind down the track.
Whether it is infringing or not is up to many factors in each case, but simply extending it is not going to protect you in every case.
If we want a definitive answer, would have to take this to a court.
Source: studied IP in Law school, but not a professor or anything.