Just how likely are the chances of a stone or other object damaging the oil cooler? I know it's one of those things you wish you'd had if it did happen but is it that common a problem?
Il second that. I had one written off on a GSXR by a stone flicked out of a twin set on a muc away lorry.
Many large piles of cash to replace the cooler.
Mine had a dent but no actual damage. I got an A4 sheet of woven stainless wire mesh and strapped that to the back of the beak. It could be zip tied to the cooler but my way hid the fixings.
I had a damaged (not punctured) oil cooler and a punctured headlight glass within a week of buying a new BMW. Not to mention the insect remains that penetrate deeply between the oil cooler fins.
I had a stone through my oil cooler just riding on normal roads, had to have the bike recovered and the repair wasn't covered by the warranty. It has a guard on it now.
I put radiator guards ( and transparent headlight cover) on my LC for the same reason...
Too many stones / dings on previous bikes and chipped headlights and windscreens on cars too over the years