I was surprised to read, recently, that the monument is unfinished after nearly 20 years due to a lack of funding. In this case it may be a blessing in disguise. While many major cities are full of spectacular public art, one rarely has an opportunity to view it in a wide open setting that is reminiscent of how reality must once have been.
What's missing, we're told, is a basket the size of a satellite dish representing their being set free to spread life. Being an artist myself, I understand the need for unfettered expression in the creation of a work. This is one instant where I would advise the artist to leave well enough alone. The addition of an element that would be foreign to the setting would, to me, detract from the spectacular piece that it is.
To add something that represents something obviously man made would destroy the natural aesthetic of it. The story about the "Grandfather Spirit" cutting them loose from the "Great Basket" is the artist's intent paralleled with paying homage to the last grand round up of wild horses in that area in 1906.
If it were me, I'd set both aside and leave those majestic animals to run free for eternity just as they are.