You attacked him, then he attacks you until he killed you. If you want that to stop, don't attack him.
But he doing that everytime I come to NCR, untill one of GMs cleaned his bugged head.
One of examples: he killed my bomber like 10 times, and I think he'll do it again and again.
My character died by this twice, and could even more, if no GMs.
This damned Sha Enin don't know how to count or has bad memory, because he want to kill me each time he see me.
P.S. My bomber exploded Sha Enin only 3 times! And first time Sha Enin ignored it, and hadn't anything again this. But after 2nd explosion he started to kill my bomber like 7-8 times in a row, and only then he remembered that he don't need to kill him anymore. So after 3rd explosion he hates my bomber forever.