The 4th circuit concluded because there were *some* places in Fairfax County Parks (specifically, 3 pre-schools) where carrying of firearms were being prohibited as those were “sensitive” places, that the challenge to prohibiting firearms in *all* parks in Fairfax County could not stand facially. [I am not a lawyer, but a facial challenge says there are no scenarios where the law is unconstitutional or otherwise invalid].

The 3rd para is saying that the Bruen decision did not apply that same facial “standard” and instead (basically) said because there are (some) areas where the law is unconstitutional or otherwise valid, it withstands a facial challenge. IE, the complete opposite of what the 4th circuit applied.

The point here is that using the 4th’s reasoning, because there is “one place in Fairfax County Parks [and thus, technically, anywhere in Fairfax County] that represents a sensitive place, it is constitutional to prohibit firearm possession in ALL Fairfax County Parks”. And the last paragraph expresses that by that logic, FFX County could ban in their entire county, or a State could ban in their entire State.