the stone thing is a specifically Hashut thing, where Hashut is taking from them to amass more power. Because Hashut is terrible, and will never be a proper Chaos God.
So. In Warhammer the ability to wield magic is a talent and training thing, and except for the divine birth controlled Lizardmen (of the non-skink or slann variety) and Dwarves, every sentient being in Warhammer has at least one example of magic wielding.
I'd find it lame if the Dwarves in DL canon were locked from magic not because of the ritual but because "nah Hashut is telling the truth they can only cast magic through Hashut, and no other divinity would give them that capability"
Well according to Gunnars without protections any dwarfs exposed to magic turn to stone. It follows that Sorcerers who actively invoke magic will eventually obverwhelm their Hashut-given protections (probably better than Valaya's since Dawi Zhar live further north yet live longer lives).