In the lengthy response I didn’t see anything that I stated was incorrect....to me it looks verified by a mastermind...
if holes were drilled into the helmet to attach the horns the integrity of the helmet has been compromised. By drilling the holes you could have relieved the manufacturer of liability.
So although the helmet might have been DOT approved....if the horns were added not by the manufacturer, there is an issue...
As a side note....helmet manufacturers recommend replacing a helmet if it’s been involved in a crash or has sustained a severe impact even though you might not be able to see any visible damage..