No, he's just saying that parent's excuse that "no" voters didn't show up because of fear of violence is invalid, because the only perpetrators of violence were Spanish police (i.e. the pro-"no" force), so if anything "yes" voters were discouraged.
The people who wanted the referendum to go through were motivated to show up despite the violence. Because they believed in their cause.
So no, the "yes" voters were likely not discouraged from showing up. Or, the "soft" yes votes were discouraged.