No, they wouldn't, because normally half of a trophy fee goes to the landowner, and half to the safari company. And even then animals considered real trophies aren't taken on meat culls.
But some of the animals are indeed mature males (or in the instance of gemsbok, females) who don't qualify as trophies because of a missing or deformed horn. And the landowner might charge some sort of fee for animals wounded and lost, because the meat is part of his profit too. And a wounded and lost 500+ pound animal represents a big chunk of change to a local biltong hunter or professional culler.
So no, they're not using Sierras because they hope they'll work.
