Empathy is not a reciprocal contract. If you only give it to those who already endorse it, you are practicing favoritism, not empathy. Kirk may have rejected empathy, but choosing to extend it to him tests our own principles rather than his.
What you describe is reciprocity, not empathy. Empathy is unilateral. If you only extend it to those who extended it first, it stops being empathy and becomes retaliation. Choosing to empathize with someone who denied it is about who you are, not who they were.