His point is that we talk of existing, as existing in this universe. But God is outside of it.
An analogy is: it would be wrong to say Tolkien exists in the Lord of the Rings universe, even though he made it, and so in a sense is a precondition for any of the characters in the lore existing.
This is actually not unusual but is the standard theological view
I think you're making a category error by thinking of companies and countries as completely different.
In the global world countries can be seen as sort of quasi-companies that happen to have monopoly control on a particular area (a monopoly that is slowly dissolving with the internet) + force.
There are many ways a company can help solve problems that we tend to think of as government problems.
1. Government also buys services.
2. Startups can fix the services government does badly as an additive product, e.g. Gusto or TurboTax.
3. Startups can solve government problems directly, e.g. Fedex vs USPS.
The only real difference between the two entities is the power of force that government can apply to make you people their services. Which is sometimes useful, but doesn't make voluntary efforts at solving the same problems a bad thing. It is also not in competition. Whenever I see these arguments being made I see people who would rather limit their work on these problems to voting once a year, instead of actually trying to solve the problems themselves.
An analogy is: it would be wrong to say Tolkien exists in the Lord of the Rings universe, even though he made it, and so in a sense is a precondition for any of the characters in the lore existing.
This is actually not unusual but is the standard theological view