Does a 10 year old horse have a future?

28-year old Quarter Horse with pal

If you're a horse, how old is old?
BLM sells wild horses over 10-years-old  "without limitation" ; they can be killed and sold for slaughter, just like young horses which haven't found families. 
 from their website:

"In addition to placing wild horses and burros into good homes through the adoption program, the BLM directly sells animals that are more than 10 years old and those younger that have been passed over for adoption at least three times." 

 After looking at the chart below, why do you think they choose that age?
Does your > 10 horse have any value?

EQUINE/HUMAN AGE EQUIVALENCY CHART

        created by Katherine Blocksdorf  read more about how this chart was made on Horses.com

Horse Age	Stage of Life	Human Age	Stage of Life
1	Foal, Weanling, Yearling	6.5	Infancy, Babyhood, Toddlerhood, Preschooler
2	Two Year Old	13	Adolescence, Puberty
3	Three Year Old	18	Teenager
4	Four Year Old	20.5	Young Adult
5	Physcial Maturity	24.5	Adulthood
7		28
10		35.5
13	Middle Aged	43.5	Middle Aged
17		53
20	Senior	60	Senior
24		70.5
27		78
30	Extreme Old Age	85.5
33		93
36		100.5