I used my whm/sch for nyzul static and discovered that I pulled hate easy on boss floors.
You're either Curagabombing (needless to say, body boosts and subsequent HP topping should be done prior to engaging the boss), have some really bad melee, or you're gradually pulling hate due to too much Cerb Hoplon or Hydra phys barrier spam (which is still not something I'd call "pulling hate easy")
If one of the things forcing you to Curagabomb is Fafnir and his wing spam, try standing next to the melee and making use of Misery+Cura. Very efficient cure and is also very light on the enmity. You can use one of these for every wing he does. (Obviously, leave Stoneskin down.) Also, if it isn't already up, make sure Shellra and a Briaulted/merited Baraera is on everyone. Depending on the rate of wing spam, you'll probably still need to Curaga, but not as heavily as you would without Cura.
Generally, with Cure 5, WHM should not be having enmity problems on Nyzul bosses compared to other healers who are much more likely to encounter such issues. Given the fact that your melees will (should) be using body boosts, it gives you mostly free reign to abuse Cure 5 without risking deaths.