You've missed the point, I think. The point does not apply to either Wenger or Grant. It is not about backing your players as such, it is about making bitter complaints and erroneously (and childishly) blaming someone else when a Liverpool player gets sent off. I have observed it in the three interviews Benitez gave after his team lost with a red card, once to Man U now and twice to Chelsea.
Other managers often don't seem to see fault in their players, most famously Wenger. But Benitez takes it a couple of stages further, seemingly repeatedly. I haven't ever noticed any other manager do that - it does seem to me to be peculiar to him.