Remember...the iron constructs are Loken's minions, and we already know Loken is corrupted by an Old God to the point where he betrays and imprisons his brother Thorim.

In HoS, it would make sense that their actions are at the behest of Loken (acting on orders from Yoggy-boy, natch) to break earthen elemental minions free from their "mother" (Therazane) and force them into the service of the Old Gods regardless of Therazane's supposed pact with the Titans.

On the one hand, seeing their actions through that lens supports the theory of Old Gods v. Therazane. HOWEVER, on the other hand (and I have no way to prove anything one way or the other...but such is the price of theory regarding works of fiction, I suppose)...what if Therazane is, for whatever reason, unable to do the work herself and has worked with Yogg to convince Loken to do her dirty work? What if, being the immortal and far-seeing manipulative creatures the Old Gods and elementals are...Therazane was just acting the part when (and if?) she "made a pact with the Titans". What if she just faked her hatred of Neltharion?! What if she's a sadist and enjoys his "fingernails down the back", as it were?! Egads, man...the possibilities are endless!!

Honestly....I really started this post with the honest intent of drawing a straight lore line with a little bit of insight....but the more i think about it..the more questions I have...and the more questions I have...the fewer I am able to answer by any means!! WHY CAN'T CATACLYSM COME NOW AND ANSWER OUR QUESTIONS?!?! HOW DO WE EVEN KNOW LOCKE WILL DESTROY THE ISLAND?!?! IS JACK REALLY THE NEW JACOB?!?! WHAT IS THE MAN IN BLACK'S REAL NAME?!!?!? WHAT IS DESMOND'S REAL PURPOSE?!?!?! AHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!