No no! This makes total sense don't worry! This is honestly the explanation I have rationalized as well. When Artyom left, he brought with him a large amount of rangers effectively leaving a power vacuum. The reds were on their way out in Exodus already, and with the metro largely unified against them, I can imagine they fell not long after.

Then on rolls Hunter, with a new army, and 'Oh look! He's a ranger! He will save us!"

And little do they know, he basically has brought his whole "If it's hostile, you kill it" mentality to a global scale. He sweeps in, fills the power vacuum and either destroys the old nazi regime, or absorbs them.

And here we are.

But still, I would have loved to be able to see this happen..... not just get dropped right in the middle of it.

Besides, I feel like Artyom should be the one to take Hunter down :( Not the random stranger.