Hmmm....for some reason, I imagine him not killing Erandur.
Granted, he IS Telvanni, and he did clone himself to make daughter wives for incist times, so morals might not be his most forward concern.
I dunno, to me, he always seemed to collect Artifacts as a hobby. Doesn't seem like he would murder someone for them.
Didn't he actually let you take the artifacts if you wanted? Once you get past the lock and all.
Basically, he collected artifacts, then ran the Corpsarium. Deciding that's boring, he invited adventurers to try and take some of his artifacts, so long as they don't hurt the inmates in the Corpsarium.
He's a rather mellow fellow. Don't hurt him, his friends, or take the handful of artifacts he wants to keep, and he'll let you get away with murder.