It can be a little gross to consider, because no ones like idea of 'the rich getting richer', but that isn't really different from what happens today, anyways. What matters most is that the system has a lot of nodes to work with, and that can still happen here if there's enough adoption in this scenario.
Not to mention that it should be hard to abuse your control in a public blockchain system. Governments could require companies to have an use photonic miner operating license and revoke it if they did something like this, for example. I think its a decent middle ground between centralized and decentralized. And (should?) produce less electric waste overall. I'm not sure, I don't really know much about photonics.