I am a cylinder inspector and as an inspector you are not allowed to damage someones property such as drilling a hole in the tank, damaging the threads ect. Second opinions are always an option. When you take your car to get inspected and the muffler fails can I damage it beyond use just because it failed my inspection? The scuba industry is the same way. By XXX out the DOT on the cylinder it can now not be used at all. This is wrong and should never be allowed.
Here we go again ... some folks think condemning is destroying. It is apples and oranges. Further a scuba VIP is not a hydro. Again apples and oranges. Reread my post - it was regarding hydro tests NOT VIPs.
For the remedial when a cylinder fails a hydro it is condemned - DOT marking are XXX out. Cylinder should then be returned to the owner. The hydro shop is NOT going to ask your permission to XXX out the markings they are going to do it.
When a cylinder a fails a scuba VIP it can be either rejected or condemned. If reject that means it may be possible to correct the issue and then pass. If condemned here again it can have the DOT marking XXX out. At this point I would not without the owner's explicit permission. Why? the cylinder may not be suitable for scuba but be fine for paint ball which has no standard other than current hydro.
Once a cylinder has been condemned it is still capable of holding pressure and it can still be filled but only privately - not commercially.
Now notice I did not mention destroying anything? If one wants to render a cylinder incapable of holding pressure then yes the owner's permission is needed regardless if done at the hydro or scuba shop.