To answer your first question, no, I don't know why I would post something like this. I just had it is all. The second question as to why the man would grab the horse's tongue -- I have no idea. Maybe that's a thing. I don't know. I'm not really a horse guy. Seems kind of odd to me, though. I can, however, at least somewhat clear up a few things from the newspaper story.
Only some really deep research could hope to turn up the name of the tongue-pulling farmhand, but I can correct the name of the horse's owner. I'm honestly not quite sure exactly what the name is supposed to be here. Garghm? Garghun? Well, I think it's pretty likely that the name should actually be Hamilton Graham. Graham ran one of the kaolin mines in Hockessin and owned a house just east of town, between Lancaster Pike and Old Wilmington Road. The house is now facing Yorklyn Road, although that portion of the road was only a private lane at the time. The property also happens to run along the Wilmington and Western tracks. It would have been a WWRR train that spooked the unfortunate horse.
I can also fill in who the "Mr. Bergh" mentioned at the end of the article was. Henry Bergh was the founder of the American Society for the Prevention of Cruelty to Animals (ASPCA). The organization was formed only 12 years earlier, and the name probably would have been more recognized then than now. The reference seems spot on, and unless the whole incident was just a tragic accident, I'd tend to agree.