His kit is designed off of a jungle role so it made sense to stack up cinderhulk with health items and give his titan's wrath some strength. Now he has to build support items on a smaller budget so he is having a harder time fulfilling his role, plus all the tank items have had their health decreased during the tank update. Scaling off of pure health isn't really working for him anymore.
Ralanr3 votesImo they should push him out of support and back into the jungle.
oSEXYPLATYPUSo2 voteshe is a tank support who would build items like 
which is all HP ITEMS , i know locket dont have hp but it scales with HP
PapaGreg211 votesEverything I said still holds true despite your comment. His gold income will be lower so he will build less items. Support items have less health than traditional tank items. All of the tank items in general have been nerfed in terms of health at the tank update.
The fact that he is still building items with health is something that I agree with so I think you are trying to counter an argument that I wasn't making in the first place.
oSEXYPLATYPUSo1 votesthere is plenty of gold as a support player now...
450 HP 
400 hp 
425 hp 
250 hp 
450 hp 
425 hp
500 hp
400 hp
350 hp
as we see here the face of mountain and ruby sight stone has more hp then most of the traditional tank items the, face of mountain is tied with spirit visage and ruby sight stone has more hp then all of them
and 2ndly the only ability of his that scales with HP is his Titan's Wrath Nautilus surrounds himself with dark energies for 10 seconds, shielding him from the next 65/70/75/80/85 (+0.1Bonus AD) (9/11/13/15/17% of his max Health) damage. While the shield persists, Nautilus' basic attacks deal 30/40/50/60/70 (+0.4Bonus AP) bonus magic damage over 2 seconds to all enemies around his target.
PapaGreg211 votesHe is a tank that has one tank ability. Having his other abilities scale on anything else doesn't really matter so his health scaling is pretty much everything to fulfill his tank goal.
To fit your narrative you left off Warmog's, which gives you 800 health, as well as Cinderhulk which is going to give you 20% more bonus health. Now combine that with the faster gold income you will get as a jungler over a support and you can see clear disadvantages to his build in that role.
oSEXYPLATYPUSo1 votesif you think he is so great in other roles right now then play it...
as someone who mains naut support he is a cc machine... his Q ... his E for an aoe slow and his ult to cc and lock down a target and his root on his autos tanks typically have low damage... but HIGH and multiple forms of cc
you can build warmogs sure but 
2850 gold it really offers no other stat but HP and if you wanna go jungle naut and go cinderhulk ok... your build would be like this
but a typical naut support build would be
this entire build is
2200g+2500g+1600g+2200g+2300g=10800g ( not including boots) this build offer 2 shields, tons of utility tons of hp and def stats and by being a support building the gold income item and getting passive gold will be easy to obtain lets you be a tank... and provide protection to your adc or other important carry with the multiple ways to cc/peel./ tank and shield while reducing damage they take
in your last game as naut you played him support
your build
2850g 
2300 gold 2500g
900g 2900g 
900g
for a total of 12350 but you dont have any way to shield by skipping the
active shield active which gives you bonus ms towards allies and gives you +20 armor when near and who ever you bind with it they take reduce damage by 12% inflicted on to you while you heal for 12% of damage they do and by getting ruby SS all of your items
all have their actives reduce by 20% due to the passive of Ruby SS so this kit works very well together and very very gold efficient
rtbf2216514121 votesHis kit is designed off of a jungle role
I stopped there.
Jungle isn't about getting your max stats. It's about ganking well.