"This is my playstyle" is a poor argument for being bad.

[RiceisNice]

The Vault is a pre 60 MSQ Instance, that you run a low amount of time like any other leveling instance before with your first class during leveling. On alternate classes you run it around 10 times.

Maybe it was his first or second time or he had no drop luck?

Ironworks is ilvl 120. If it's their first class, there's absolutely no reason not to have upgrades because the MSQ feeds you Ilvl 139 HQ gear. If it was not their first class, it looks just as bad from a different perspective because they know there are vendor sources of gear and to have the common decency to not go into a Ilvl142 dungeon in ilvl120 gear, or especially if it's not their first healer because they have gear spilling over from leveling their first healer.

Hard to know without seeing what exactly happened.

Maybe it was to much to handle for him.

Maybe you miss the fact what levelsync really means.

Maybe you are not playing as good as you think. Pulling much is easy. Knowing how to handle it correctly "as a tank" is a different thing. Its not just a healer thing

He did mention that the healer apparently got offended for being told that he was indeed undergeared.

I told them that I haven't noticed that they were so undergeared... you wouldn't believe how much offended they got.

You entirely opted out that part in your quote, and it does not make the healer look any ebtter than a tank who overpulls. They're taking a statement that possibly was not meant in offense in offense and may have gotten pissy about it. Eithercase, the healer was in ironworks, got mentioned he was "undergeared" and got offended by it. That's the same as anyone getting offended for saying they're not playing good (and especially if they know it).