2004 X5, 3i - Front Caliper Piston

[2004bmwx53i]

Hi everyone,
During front right brake removal, I noticed both pads were hardly worn. Rear pads were completely worn out; all pads were supposedly renewed couple of years ago by an indy couple of years ago!
So I thought it's because of the jammed piston. With a lot of back and forth moves I managed to push it completely out, as seen on the attached picture.
My question is, do you normally clean the rust, lube it thoroughly and let it go; or do you replace the whole thing altogether.
Thanks,

PS- During all this time, I never noticed any drift on the steering during braking, nor any other driving issue at all. To it's fascinating to see how the system work under these conditions.