If a fetus is viable, it most certainly is a person. Whether it is inside or outside the womb is irrelevant. That would be like having this discussion:

Me: Wow, you have a large pine tree in your kitchen!

Liberal: We planted a seed in some dirt. It isn't a tree.

Me: It is clearly a tree. I am looking at it right now.

Liberal: It will only be a tree when we take it outside. Right now it is a seed.

Me: The location doesn't matter. You have a tree.

Liberal: You don't have trees inside. Trees are for outside. It will become a tree when we put it outside.

Me: I'm not living in your fantasy world.