This is a real issue that is difficult enough without obfuscating the discussion with trying to act as if you alone speak for God on the issue of horse slaughter.
We are also commanded to be good stewards of what we have. Good people may argue the definition of cruelty, but if we could come to agreement on what that is, then it is ~not~ immoral to attempt to prevent cruelty to creatures, it is immoral ~not~ to.
You misunderstand that I somehow think I alone am speaking for God. The biblical tradition I'm elucidating is part-and-parcel with Western practice of nearly 2000 years. Only in the last 30 or so years, with the rise of the animal rights movement--soaked as it is in pantheistic eastern philosophy--has there been confusion.
As I understand it, these horses are marked for destruction anyway, so they could be put down, and buried or wasted, or without cruelty, used to help people--both those who choose to eat horse-meat, and those who work at the plant. Someone like Bo Derek could probably afford--along with some of her fancy friends--to buy the plant if they wanted to, and find jobs for all the people closing it would cause. Instead, they go to law to try to push their mis-guided values on everyone else--the people involved be d*mned.
"Good" people may argue, as indeed they do, that any use of animals to help people is immoral....welcome to the wacky world of PETA. However, America is not controlled by people of a pagan non-sensical philosophy of Vegan ideals, rather by the mainstream longstanding idea, that stewardship demands care for, and decent treatment of animals--even ones bound for the meat-packing plants. To single out horses though as somehow beyond the rules applied to all other animals, is however sentimental and silly.
I for one have no desire to eat horse-meat--nor monkey, nor dog, nor caviar for that matter--however, I cannot push my personal tastes or squeamishness on others in the name of universal values.
That's why its valuable to have a source of universals, so I can tell the difference between right and wrong vs. my tastes and other's tastes--and that source is something many in America, even conservatives, have forgotten.