As much as people make fun of Shadow for his Maria flashbacks, he hadn't had one since he resolved his issues in his game. So it was nice that people were generally concerned and moved to see him tweaking out for what could've been with Maria.
He might already move on but the guilt's still there.
That's why when there's a possibility to bring her alive, Shadow is considering it.
For all we know it most likely be a trap and Shadow knows it too, but he's definitely facing it to make amend to himself.