I like it, I don't mind the way it sounds. I personally don't find it too Biblical at all, that doesn't bother me. I think
Kai (the sound of that name, not really the spelling) makes a good and obvious nn. I like:
Malachi JohnMalachi DavidMalachi PeterMalachi RowanMalachi JudeMalachi GeorgeMalachi HenryMalachi ThomasMalachi Seth