On the face of it that sounds fair enough, but actually it is deeply confused and offensive. Funding for traffic calming should go to where it has the greatest benefit. If this correlates with poverty, then more of it will go to poor areas, as it should. But where there are accident hotspots in prosperous areas these should be dealt with on an equal basis.
The idea that poor areas should get priority just because poverty correlates with risk, is a bit like saying you should hire tall people when you want smart employees because height correlates with intelligence. (You shouldn't, you should test your applicants' intelligence.)
The suggestion here is that the life of a richer child is worth less than the life of a poor child, and that is grossly offensive. The implication is that reducing child deaths is not the policy goal, but rather equalising child deaths across the social divide, as if this were a front in the class war.