What I see here is a service that allows people who didn't plan far enough in advance to be able to enjoy an experience at a premium (or maybe a fee/penalty cost) that they otherwise would not have. The customers of this service have already incurred a penalty of sorts.
I don't see this as (yet) an abusive economic system that disgustingly inflates prices in some sort of a monopoly-style hierarchy (which ticket scalping does). There is unprecedented room to badly abuse this system, and I would hate to see that happen.
However, I think what he did should not incite so much hatred. I personally am against this sort of thing but that doesn't mean I am going to spread hate. Ticket scalpers, though...
In another variety, I've seen newspapers/blogs do this sort of advanced-fake-reservations and give them away as prizes. I'm not sure which is worse.
I would hope that restaurants take measures to make these kinds of things difficult to pull off. Maybe assess some additional tip amounts if the reservation name doesn't match anyone in the group, or asking for an ID when they first enter the restaurant (although I think this would be bad customer experience).
There's so much room for abuse with solutions that needlessly disrupt the experience.