In general yeah it's normal but it shouldnt be a problem for your healers keeping him up in hc content, also you dont need to babysit a paladin tank either, i cant count the times where our healers are just flat out bored and spam healing me so i never get to use hand of the protector on myself for selfhealing.
As long as he is healable i dont see a problem, healers also have to adapt to different tank speccs, just because druids dont need heal ever doesnt mean that you can ignore a paladin/vengeance dh in more challenging content.
If your mate uses light/hand of the protector more often you healers should notice it, he can also try it with the legendary helm, the self heal has 2 charges with it equipped, if he has it.
Gearwise, get him his 4 piece bonus, gives him 5% reduced damage basically for free.
Also you yourself as a warrior you are all about physical damage, Tomb of Sargeras is in the more challenging encounters all about high phys dmg making your critical block chance that much more better, paladins do way better on fights that have more magic damage going on.