Yes, of course, most of us already knew that Richard Spencer was a virulent racist. In that regard, the leaked audio of Spencer snarling racial epithets in a foaming rage comes as little surprise. And, yes, the circumstances of its release are likely a media play by an erstwhile ally trying to regain lost currency (both literal and figurative) by playing one of the few cards left up his sleeve. But the exposure of Spencer's tirade may still matter, if only for the way it contrasts with his very carefully groomed public façade.
Many have criticized certain media orgs for burnishing Spencer's social capital with glossy photo shoots and soft-ball profiles, and rightly so, but it's also important to remember that Spencer aggressively courted the ambiguous coverage by packaging his brand of white nationalism as something new. The pitch was effectively "ethnic nationalism without racism." Accepting that pitch meant buying into the premie that a person could insist on the creation of a new, segregated world order out of something like a sense of equality. Each race would have their own racially pure nation-state, each of which would respect the other's dignity and sovereignty by staying well out of one another's affairs. Alt-right demagogues like Spencer offered a number of rationales in support of that vision, but the audio of Spencer makes them moot. Whether or not you could, in theory, construct white nationalism without it, racism is the motive in fact.
That may already have been acknowledged among left/liberal critics of the alt-right, at one end of the spectrum, and the more hardline organized racists supporting them, at the other. Yet, there are two groups in the middle ground for whom the exposure of Spencer's virulence may still matter a great deal. One you could charitably call the Uncertain: People who, for whatever reason, found it at least plausible that you could construct a racism-free brand of white nationalism. The leaked audio may go a long way toward disabusing them of that illusion. The other group is the Genteel, who sympathize with racist views and institutions in varying degrees, but only to the extent that their racism can be covered by a measure of plausible deniability. For the Genteel, getting caught on an explicitly racist tirade is an unforgivable breach of decorum, punishable by a total withdrawal of support, if not ostracization.
For overtly racist organizations, losing those two groups would be a step back, ultimately leaving them were they were at the turn of the century, when public attitudes toward civil rights and equality were at high tide. But for a ideological broker like Spencer, whose entire career is built around the mission of making white nationalism palatable to the middle ground, the loss could be devastating.