That's a broad claim, you have to prove your case. You're asking for a ban on vertical integration as a business strategy.
OpenAI wanting to vertically merge to make their own AI chips may seem harmless enough (it's a good business move, we can cut expenses)! But we can't forget that Sam Altman just a few months ago told Congress he supports making an organization that companies need permission from to being creating/utilizing advanced AI systems. And he's such a kind man he's willing to lead that organization himself.
Obviously someone integrating the chips to train AI, and having the ability to approve/deny his own competition is a huge red flag.
NVidia has a near monopoly on the AI hardware market right now, so some vertical integration of alternative AI hardware doesn't seem nearly as big if a deal if it is needed to fight that current monopoly.