[qubex]

It clearly would be discriminatory (in the broadest sense) because it creates a distinctive criterion that a priori defines who can, and who cannot, apply. However, ‘discrimination’ is just a synonym that has taken on all the negative connotations of distinguishing (a word with whom it shares a common root) and therefore one should sometimes wonder whether or not all ‘discriminatory’ acts are prima facie ill-advised. If you can rephrase the criterion in terms of distinguishing between different groups you’re (probably) on an ethically defensible high-ground.