The structure of feeling we're talking about is "white victimhood" and it was introduced into the body politic by Richard Nixon in 1968 and and perfected by Ronald Reagan more than three decades ago. 

It has NEVER been challenged in the years since and it is VERY widespread and deeply rooted. So, yes, in fact many white folks who hear Spencer and company already feel like he does, it's just that direct expression of those sentiments has been discouraged for so long that those folks have no idea who they really are.

In other words, they always already feel that they are "victims of liberal censorship". We're only just now beginning to understand how deep these feeling are. They're not "the choir" so to speak, but simply by hearing their deepest resentments articulated directly they can be converted.

They've been subsisting on the thin gruel of GOP dog whistling for so long that Spencer's ilk must come as something of a revelation to them. The ACLU approach misses this.