[specialist]

I reject Bork's novel premise that sole criteria is consumer welfare. Proper antitrust assessment is based on competition.

Rephrasing your point:

Both grocers and aggregators compete with their own partners.

At the very least, in house brands shouldn't have unfair advantage.

https://en.wikipedia.org/wiki/The_Antitrust_Paradox

[marris]

Can you elaborate? All of the examples I can think of where favoring an in house brand is "bad" ultimately end with the consumer being harmed by either paying a higher price or receiving a lower quality product. What are the other "bad" scenarios which don't reduce to either of these?

[specialist]

The Sherman Act doesn't say anything about consumer welfare. It doesn't matter if the price goes up, down, sideways. What matters is illegal anticompetitive actions.