If the Level IV multiverse model is true, would it undermine cosmological arguments?

The multiverse isn't necessarily a problem for cosmological arguments.

However, *hypothetically*, I think that Max Tegmark's Level IV multiverse hypothesis might cause a problem *if* it were true, because according to this model, mathematical structures are necessary.

If it was true (and Max Tegmark seems to think it is), would it be a problem for cosmological arguments?

Why is saying 'God is necessary' better than saying 'mathematical structures are necessary'?