(very late reaction sorry)
I love Iron Bundle and I think it has a chance at being a healthy presence with the Booster Energy update. Modest Agility (cleaner) and Timid booster (cleaner/revenge killer) sets should be manageable now. Freeze-dry helps contain Palafin to a degree, which is massively important at this stage.
Specs will become more of an issue now and I haven't seen much viable counter-play to this yet. Its higher maintenance and prediction reliant, so most haven't bothered so far, but as people start building teams around it I can't forsee what the response will be.
It can use tera well but it doesn't double its viability like it does for something like Roaring Moon, so I don't foresee it spiralling out of control too quickly. It's incredibly good, but I think its a risky Jenga piece to pull out right now.
If I may interject, since i figured i should maybe try to take part in those discussions, I don't think that's much of an argument in favor of Iron Bundle but rather the opposite.
As a side note i've been playing competitive for about 10 years now? But never decided to be part in tiering discussions, but that line of logic comes in many shape or forms whenever something balantly strong or broken is being discussed out.
First being, Palafin shouldn't be considered in deciding whether Iron Bundle is healthy for the metagame, as it fails to adress all of the subsequent effects it has on teambuilding and the metagame as a whole. Scarfchomp checking M-Metagross doesn't really make it any less broken, and in the end, tiering decisions must come from weighing out those variables in order to determine if there is satisfactory counterplay in the metagame.
Secondly, while it may be high maintenance or prediction reliant, its duo STABs together are too good, I find Freeze-Dry similarly with Kyurem to really push it to the edge. And as part of my personnal experience, i have personally been pairing it Chilly Reception Slowking (which i don't see too often) in order to freely pivot into it to spam Specs Blizzard, it lets it survive banded Mach Punch from Breloom (unless tera) or it only gets 3hko'd by banded Scizor BP.
If anything, the fact that it doesn't rely on tera works in its advantage, since it opens up the gimmick for one of its teammates.
It may come from my biased POV, as i find Chilly Reception to be absurd (atm im using it with Bax and Iron Bundle) but even without that, the strains it puts on team building are way too much with the current means we have.
I don't even like the idea of calling this "powercreep", we got a lot of really outstanding pokemon powerwise, but people tend to forget what we lost in return ie: Fini, Lando-T, Clef, Heatran, Buzzwole, Ferrothorn, Zapdos or even Melmetal and I must be forgetting a lot more, pre home/DLC tend to be pretty chaotic but we've seen before how the metagame can change after only a few more inclusions. And while i would PERSONALLY find Flutter Mane with Heatran around more bearable, it is fair atm to enact policy and quickban stuff for the current metagame, and then consider what is the best course of action with every card in hand.
I really love Palafin and i think it's pretty stupidly limiting atm, so i wouldn't be surprised but sad to see it gone but so be it. Wouldn't want Koraidon in the tier cause Dachsbun keeps it in check.
Not to say this was the entire premise of your argument since i just wanted to pick up the discussion from there, i see your point of view but it's really hard to justify Iron Bundle's presence with its nearly unmatched speedtier, conditionally good bulk and insane coverage atm even if it keeps Palafin in check tbh