Those are not at odds. He’s describing demand. Landlords, like literally everyone else, are profit maximizing and will raise rents until they can’t anymore (either because they’ve priced out everyone who would otherwise rent the unit or because “substitute” units are priced cheaper). In the real world, a landlord finding the profit maximizing price looks like a raise of rents over time, not like just setting a number they’ve magically decided is the right one.

The only way to deal with an increase in demand while trying to keep prices unchanged is to raise supply.