A somewhat rude answer may be that, despite being very old, University of Salamanca is not prestigious -- outside of the top 500 in all major global university

A somewhat rude answer may be that, despite being very old, University of Salamanca is not prestigious -- outside of the top 500 in all major global university rankings -- and is therefore more likely to be willing to employ somebody who can fake their way into appearing to be a high-impact researcher.