It says in that article that he was wearing full racing tack-- the horse in the picture appears to be wearing cavalry saddle/ curb bridle? Also Shergar was a bay with a blaze according to his picture on pedigreequery: http://www.pedigreequery.com/shergar
So it's definitely not him in the photo. Seems unlikely to me.
Ah, good. The confusion stems from that a plumber apparently DID just find a huge, hidden store of cash in this house, which was owned by a former IRA member who is currently up on charges stemming from a shaky land deal and subsequent bankruptcy. So there is just enough true news stuff there to throw me off. But I just couldn't imagine the horse had been in some dude's kitchen for 30 years without SOMEBODY spilling the beans.
It's not that I think that this story has a happy ending, but this just struck me as particularly awful.