Breeders and stud farm owners in Kentucky looked at Michael Blowen like he was crazy when he first pitched his idea to them a decade ago: Open a retirement farm for pensioned stallions and make the most famous of those retirees a tourist attraction for racing fans and horse lovers. The response wasn’t encouraging. Most people didn’t think a retired film critic for the Boston Globe was qualified to handle stallions, and many considered him overly sentimental about breeding stock. Ten years later, with 117 retirees in his care and about 15,000 to 18,000 annual visitors to the 90-acre Old Friends headquarters at Dream Chase Farm in Georgetown, Ky., Blowen is proving that his idea does work. And he’s still unapologetically sentimental about the animals he considers heroes and celebrities.