It depends on whether you think God is there or not.
If God is there, trashing a mountain is trashing something He made. That's not cool. (Humans still have greater moral worth, because they are also something He made, but are more "in His image" than the mountains are.)
If God is not there, and nobody else will ever see the mountain, then I can destroy it without it impacting anybody else. I still become a person that destroyed a mountain for no good reason, though, and that impacts me - it affects who I am and who I become. (If I have good reason, if it gives me something I need, then the moral calculus still tips toward me being able to do it, because morally I outweigh the mountain.)
Your last two paragraphs... why does moral weight arise from feelings? Why not thoughts? That seems like a rather arbitrary choice, especially if the feelings are purely from biochemical processes. Don't thoughts also arise from biochemical processes?
And that leads to a nastier question. Are "morals" just a subset of "feelings"? Are they also just biochemical processes? If so, first, do morals have any actual validity? And second, can we expect an AGI to have anything resembling morals?