I feel that if anything you're the one being situational here :/ Both Hp Ice, Hp Fire and Clear Smog are all used to counteract certain threats, I'm not saying anything more than that. Inevitably there will be pokes that Amoongus can simply not handle, that's what other pokes are for. For instance, if you need to hit Scizor, run Hp Fire. If you need a jump on 'Mence, run Hp Ice. You seem to think that Amoongus is supposed to be tearing through pokes, and that simply isn't his place. Clear Smog, Hp Fire or Ice, all of these are simply to prevent him from becoming set-up bait, maybe to net a surprise KO on a predicted switch. Amoongus has modest offensive stats, and his main role on your team should reflect as such. Consequently, just ignoring the viability of such an option is a tad short-sighted, no?
Also, minor nitpicks to calm my OCD, Bulky DDnite usually runs Adamant w/48 Atk EVs, in addition to often running Dragon Claw over Outrage to avoid the unsavory lock-in effect. Thus a max attack Adamant Dnite would likely be a CB set, which is an entirely different beast to deal with. Also, 120x1.5=180, not 160. And on a side note, Hp Ice off an uninvested Amoongus nets a 2HKO on both Gliscor and Landorus where Giga Drain hits around a 3 or 4HKO, so it does have some use there. Either way, I can see your point here, and I respect that, I just want to present another point of view.