The Fault of The DPS

 I didn't withhold heals from him. He died before I could heal him. I let him know when he was standing in something bad.

If he wants to continue standing in something bad after being told WoW accounts for sale (and he WAS NOT, so thanks for missing that part), then I have better priorities to keep alive at that point.

And frankly, that was the lesson that I was taught when I started. Maybe it's cushier for you these days, but if you or I or someone else is going to keep standing in crap on the floor, then heals does not have priority to heal you, me, or someone else. If I die in a purple puddle on the floor, that's my fault for standing in the puddle.

 I don't  really know how to respond to that, except L2P. I've seen healers (and done so myself) keep people alive through constant avoidable raid damage (sand traps, lightning, whip, etc) with far lower ilevel, and no mana problems. 

Maybe consider revisiting your spell priority list?

I will reiterate, because it seems like my point is not going through.

If the DPS dies while the healer is trying his best to keep him alive, it's the fault of the DPS.

If the DPS dies because the healer made the intentional choice not to heal him, then it's the healer's fault. 

No content, not vanilla, Where to buy wow accounts not BC, not Wrath, has ever encouraged the completion of encounters by allowing DPS to die. Not a single one (except Azgalor and Gorefiend I guess, but they were special).