There is an easy fix. Drill and tap the mount with a left hand tap and apply a left hand capscrew. It don't have to be ISO, it can be SAE so long as the tap drill matches the major diameter of the existing threads. Basic rule of thumb is 75% thread is acceptable. Tell me which bolt it is and I'll tell you what the SAE or metric equivalent will be. You can then buy a LH tap (I'll tell you where to get that too) and any fastener place will have the LH capscrew.