Cursed Crypt Boss and Tombfist PK?

I died to the Cursed Crypt boss last night, map tier 10. He's the large skeleton guy who will do an AOE elemental nova blast if he's cursed. I made sure to take out my blasphemy curse as to not PK myself. I still got one shot with 7100hp from his curse reflect nova, and I was super confused as to why.

Is it possible my tombfists with intimidation PK'd me?

This has happened to me three times this season, all on my Occultist. Turned off all of my curses, and he still does the curse nova.

The game must be considering something non-curse as a curse. That is the only explanation I can think of.

I use a Wither Totem + ED + Blight for single targets. Perhaps one of the debuffs conveyed by these abilities is being considered a curse. Perhaps Occultist's "Malediction" counts as a curse?

Whatever it is, this is extremely frustrating. His nova ability goes through capped res + 6500 ES immediately, and is a death sentence for anyone who mains blight and has no movement ability, which is why I always disable curses before entering the boss room. And yet, he still casts the 1-shot nova... ugh.