Time to put my uneducated American hat on. There are workplace safety regulations and each of those were written for exactly humanoid physiology, and factories are very streamlined to be the cheapest possible way of adhering to those rules. A centaur has good odds of making a manufacturing workplace unsafe by virtue of "being horse shaped and size."
Now, you might argue that the anatomy of a centaur in this case would classify as a physical disability under the ADA and that the glue factory would have accommodate a qualified centaur. But the American with Disabilities Act already has a clause that accommodations that would cause undue hardship are not legally required, and considering the evident rarity of a centaur body type one might successfully argue even just taking the time to make sure that your workplace is Centaur-OSHA Compliant would be a major investment and would be too strenuous on the company, even if you find that you don't have to make any changes. So no, I don't think you would hire a centaur as an employee.
I'm not a lawyer. But I do know that absolutely a glue factory would accept a centaur as material for making glue out of, and my reasoning is too bleak for the funny animals fighting ring webbed site.