I'm searching for the logic int hat post and I just... can't... find any...
First off, Jack is nothing but a mask. A MASK. Last I checked MASKS don't have life. Is your imagination really so bland that you can't think of ANY way for him to come back? There are hundreds of ways LH could write him in if they so chose to.
"Jack's spirit escaped from the mask before it hit the magma"
"Not even the hot flames of the volcano could burn such a powerful artifact"
"Theresa, seeing that Jack had a future destiny, saved him from the flames and keeps the mask herself for future use"
"The volcano is now inactive, and at the very bottom lay the remains of Jack's mask. A power hungry warlord has it fetched for him, repairs it, and puts it on."
And those are quickly though up ideas. Call it asinine all you want, but it is still more prudent than your argument or any argument you have posted in this thread.