It’s not the author’s logic. It’s the court’s logic. Contracts are messy in the real world. Sorting it out can be tricky. The various doctrines of estoppel are

It’s not the author’s logic. It’s the court’s logic. Contracts are messy in the real world. Sorting it out can be tricky. The various doctrines of estoppel are relevant for sorting things out. Of particular pertinence to this case, “conventional estoppel” means that if both parties consistently behave in a certain way that can become an expectation to be relied upon (over-simplified!) In this case, if the guy reasonable relied on the convention that he would be notified when they expired, and wasn’t, then he may have an estoppel claim. There is a large framework around contract law that takes a semester in law school just for the introduction.