For why? I use raw organic apple cider vinegar from health food store for a lot of things. It's antibacterial, antifungal, antiviral ... and I don't worry it will burn or hurt. Let's see what experts think about the hydrogen peroxide.
Carefully wiping some on and then rinsing should not hurt anything, but why? Is there a problem? There might be other things that would work better depending on the issue.
Why would you want to use peroxide on the shell? If you want to clean the shell just use water. Hydrogen peroxide can cause damage to healthy cells. I don't think it would do a lot to the hard keratinized skin cells of the shell, but I just don't see the reason.
When I bathe mine daily I just use a soft baby toothbrush gently on his shell and the water in the tub. Not sure if you need to wash away something more specific, but this works for us because he is in a very "soily" type substrate where it can get pretty dirty.