I suspect you'll find a correlation between age bias and economic success for businesses. That may be a positive or negative correlation. And that may vary across cultures, industries, etc. Maybe old Mexican women are statistically just as good at nursing as young white women, but maybe old American white men are not.
I'm not presupposing age discrimination would be successful, I'm suggesting that no corporation, economist, or politician would likely be willing to publicly acknowledge that age discrimination is good for business.
The question is, if it could be proven that hospitals who hire more old white American male nurses make less money than hospitals who hire old Mexican female nurses, what differential outcomes would you be willing to accept? Would a company policy discouraging hiring old white men be okay?