Just outright Spire them to show them who's the boss!
I was going to say something about Sprint but realized the changes make it irrelevant; I like the way you think.
It got some nerfs in stormblood but it is by no means useless. For anything less than savage content, what class you run as doesn't really matter. For savage the prevailing wisdom seems to be that you want to bring an AST no matter what, but the other healer can be a WHM or a SCH.
Basically; Balance makes AST's group utility OP to stupid levels, and Noct shields right now are good enough that barring a deployed Adlo being nigh-mandatory you won't miss SCH shields. WHM can't mitigate or do much in the way of utility, but the rest of the party can kind of band together to cover WHM's lack of mitigation and their raw heal bomb capacity should make them solid for progression recovery (even though ideally you don't want WHM spending GCDs actually healing because they have the highest personal damage per GCD of all the healers, "pure healer" my foot.)
I still maintain Diurnal AST/SCH will edge WHM out in optimization mostly because Chain Stratagem is going to be really, really good for any job with a crit mechanic, and while the fairy heals took another hit in SB they can still do a decent amount.
It's mostly a weird situation of I kind of think Noct's shields are overpowered currently, but the only people who would really suffer from Noct getting a massive hit to shields is WHM, because Balance is still going to make AST borderline auto-include.
We're doing prog on Noct/WHM but I'm going to at some point level SCH and learn to use it so we can try messing with Diurnal/SCH at some point post-clear. Infinite 'why doesn't the fairy ever frigging listen' posts, coming soon.