In this scenario you have made something and it is available for purchase. A landlord creates nothing and will not sell so that they can benefit from scarcity.

He's basically talking about the digital equivalent of "what if i built a saw mill and then got income from people using it." Just because he created something doesn't mean the income received after is not a form of rent seeking, it's profit derived solely through ownership of the thing that was made despite the labor that made it potentially having already been paid for multiple times over, and since all this income accrues passively with no labor input beyond the initial creation, it's passive income