These priests lack a solid theogical education.  The idea of inclinations comes from the Summa, I II Q 94 art 2.  Also, celibacy is not the same as chastity. Celibacy is the renunciation of one's desire that flows from the natural inclination for sexual acts and the education of children.  A man with "deep seated inclinations" of homosexuality lacks the desire that flows from the inclination to engage in a sexual acts with a woman and raise the children that may result from that act.  
A promise of celibacy is first a renunciation of the natural right to engage in the conjugal act with a woman that is founded on a natural inclination and desire. Men with deep seated inclinations of homosexuality lack that desire as a result of an improperly ordered inclination.  There is nothing for them to renounced. This is also an essential aspect of a male only priesthood.