Humanism as Transhumanism

Stanley Rosen gives his--let's call it his post-Straussian take on the contemporary political relevance of the Republic:

When philosophy seeks to bend the city to its will, it turns inevitably into ideology and tyranny. From this standpoint, we can regard the contemporary effort of the biological sciences to transform human nature as the "postmodern" version of Platonism, in which the rhetoric of scientific progress replaces the altogether less politically persuasive doctrine of the vision of Platonic Ideas. History as it were triumphs over eternity, but the motivation is the same: to protect humanity against nature. It seems heretical to attribute this view to Platonism, in however degenerate a form, but the point follows directly from the doctrine of the natural division and illness of the human soul, and the correlative thesis that this illness can be cured only by philosophical psychiatry.

The sly implication of transhumanism in an antagonism against the open society strikes me less than the possible implication of visionary education. For what is "seeking to bend the city to my will" if not seeking to prosecute a programmatic, efficacious transformation of the human soul?