There were more factors than that. One was the burgeoning hegemony of the Wintel architecture, standardized with the PCI bus, cheap disks and fast interfaces, etc. The ability of BSD and Linux to leverage this hardware figured mightily into toppling the proprietary giants of the Unix world. Some of these vendors even realized it, such as Sun Microsystems, who introduced PCI-based systems late in the game.

I'd say it was a perfect storm in this regard. Sure, the lawsuit gave proprietary Unix a bad name. But that, in itself, wouldn't have been a death knell, if it weren't for these other practical factors.