m1lkb0x

Its up to you really. You could probably get away with just a finishing polish and resealing it up again. 
 
And I would pick up a “do not wash” mirror hanger. At that point if they mess it up, it’s on them to fix it. We give one to every client who gets a coating done since they’re harder to fix. 

Oxidation usually has a rough feel to the touch. If it’s smooth, it makes me think something in the clearcoat or failure. 
 
If you have a repaint in the back of your mind, you have nothing to lose by attempting to polish it out and see what it does. Do a test spot and see what happens. Worst case is your worst case scenario comes true. 

In looking at the Mustang I'm working that has clear coat failure, 
this does not look the same even comparing the untouched vs the test spots.   I linked in the discussion since there were several good discussion points and pictures included for comparison.  this particular car does have some similarities to both a Chrysler blue and Toyota blue that had paint failures I looked over the last year or so.

On one hand it looks like it, but on another almost looks like something was applied to it as well, strange patterns in it for CC failure. Seen stranger thou so never know. I would want to be careful around it no matter what. 

Looks like clear coat failure to me. Running your hand over it won't tell you that as it could still feel smooth, in my experience. If indeed it is, taking a polisher to it will only make matters worse, and only a repaint will fix it. I'll wait to see what others think. Adding @shane@detailedreflections, @mc2hill, @TheWolf to get their inputs...

Im not a professional but I had this same issue with my 93 RX7 and I was not able to polish it out. The surface was silky smooth after a few passes and there was no scratches on the surface but it still looked like this. Im pretty sure the issue is the paint under the clear coat.

Waterless Wash & Waterless Wash MF towels..... great combo!
 
 

Waterless Wash, or Rinseless Wash diluted 16:1 (for a waterless wash-like solution), and the Waterless Wash towel is ideal for dust. DS will work great, too.

Rinseless Wash. Wonderful stuff!
 
 

We have a trunk deck from a corvette a client gave us to polish out and play with. Also a spoiler from a Volvo S60. I need to polish out the trunk deck and apply different coatings so people can see the difference. Then film over part of it so that can be visualized as well. 

I have multiple practice vehicles, but I don't tell the children that I use their vehicles for testing.  The kids are always happy, they get free detailing along with touch ups and I get to learn about the products and usage methods.  My wife's car also gets some testing, only because she get any new products used on her car first, but I'm real careful on that one.
 
As for the variances in the paint, I am finding more variance between the years than between the manufacturers. We have red vehicles from 1994 - 2017 and many manufacturers, Chevy, Ford, Lexus, Mazda, Range Rover, Subaru and Toyota.  Nearly every vehicle is Red, so that does help level the field for learning the products and comparing the differences.  I'm not sure you would get the same comparison if you were trying different chemicals/techniques on a White and Black panel to compare.