Both caliper stabilizer bolts are tight, as well as the caliper bolts. No movement in the assembly. Will sand it a bit and move on with my life. The disk should be a lot harder than the pads!
Yes it should be, but hard grit can get in there. Can't really tell in the pix, but in the image looking down at the rotor, it seems like there is a crack or other metal defect in the rotor at 10 o'clock. Check out the pads for grit or foreign matter, sure. If you sandpaper the pads, use only hand sanding, because a power sander will take material off, unevenly. DAMHIK. Then you would need new brake pads, no
If the rotor checks good, did you loosen or remove the caliper bolts? If so, loosen all the same bolts again, and have an assistant apply the brake firmly while you tighten all of the caliper bolts to the correct torque specs. The wheel should turn freely, when the brake lever is released. Make sure the brake lever pivot is clean and lubed, not gritty. The brake lever must move freely.
Make a cautious test ride in the neighborhood only, not on the open road. Use that brake sparingly at first. Stop and check the brake rotor often, and if it is getting too hot to touch, then you have a problem that will not
fix itself. I once saw a bike on the freeway at night, and the rear disk was glowing
red-hot. I blew the Blazer's horn at him, four short blasts (collision alert!). He immediately dove out the exit and waved thanks. I could not follow him out, due to traffic, but I saw that he got stopped without incident. Can't say more than this, but he would have needed to wait an hour to cool off that brake. Don't ride with any brake-heating problem; once the brake fluid boils, and it will, things can go bad fast.