God Being Timeless Doesn't Avoid an Actual Infinite

A lot of theists believe that an actual infinite is impossible, this is usually because they want a convenient way to argue for their God. However, if God existed eternally, then there would be an infinite past, and thus, an actual infinite. So they say God exists outside of time to avoid that problem.

I feel that they cannot actually say this avoids the problem:

Consider, will the universe ever end? Will there be an eternity in heaven? If there was an eternity in the past, then we can consider that an actual infinite, but what about an eternal future?

Think about God existing outside of time, but having an infinite future? If God existed outside of time, and he created something, and it ended, he would experience it in literally no time. But what if God existed outside of time when there is an endless universe? Would God experience this in no time? That would imply an actual infinite.

To help someone understand this problem, imagine there is a world where all that exists is someone counting for eternity, it never ends. Now imagine that there is a being watching over it, which exists at literally every possible point. This being literally saw all of the counting. This is clearly an actual infinite.

The thing about this is, I don't think an actual infinite really is impossible. We simply don't have a solid understanding of what they are. I'll let the theist decide what they think.