Well there you go. It might explain how the calliper drifted onto the disc at some point if the bolt let go.
I had to get a replacement bracket for mine when the powder coaters lost my original!
If I recall, it was about £60-£70 from Moto Rapido with 10% UKMOC discount. Note that you have to buy the bush in the bracket separately and press it in yourself.
Luckily for me the powder coaters footed the bill, but they probably wouldn't buy you one?
As Slob says, nothing wrong with a properly done helicoil. So long as the calliper is still pulling down flush to the bracket and not being held out of line in any way.
2V cam belt tensioner bolt thread holes are helicoiled from new btw.