No, you are not getting the point. That is not a handful of emails, it's thousands of emails to one columnist and we have already seen that there are millions of messages like that going to people who the Trump-fans see as enemies.
The columnist said "hundreds", not thousands:
I have, however, heard from hundreds like “Matthew,” who worries about “immigrants” and “Gerald,” who thinks people of color have an “alliance” against him.
(emphasis added)
That is not a small difference. It's an entire order of magnitude. Even if we take Mr. Pitts at his word and assume that all of the emails he talks about are what he claims them to be, and that each one was sent by a different Trump supporter, they still represent a
very small portion of all Trump voters, less than 0.1%. Moreover, the sampling method (unrequested emails sent to one columnist) is woefully inadequate, or at least it seems that way to me.
These people are the loudest Trump supporters and more than a tiny minority. The others either have their heads stuck up their assess or fully accept them as the representatives of their cause because there's no way otherwise to miss all this hate they spew.
Maybe they're the loudest because the media focuses on them the most. You don't even have to believe the media is trying to smear Trump supporters to consider the possibility. Focusing on angry, belligerent extremists is good for ratings.