May the Prophet Muhammad be pissed on by all infidels

Whoever insults the Prophet (PBUH), if he later comes and apologizes, and kisses the shoes (of the ruler), and says, “I want all Muslims, every one, to return and strike me with the soles of their feet” — does the ruler have the right to accept this?

I bring up this question, as it was asked of me. The answer is that it is not permissible for anyone to accept this. Then what do we do with him? We kill him! But he told you that he repented. We still kill him, even if he repents!