Hard to tell what actually happened on the court, and clearly none of us were at this match so we can only assume. Its disappointing to hear that the constant smack talking in the sport has turned to assumptions of racial slurs, and even more disappointing that it becomes a twitter witch hunt; but that is 2018 for you.
Smack talk in college tennis has been around for years. I used to play guys all the time in the early 90's who would resort to this type talking/mind game tactics, especially if they were losing and especially in the mid-major/small program matches which are less observed by officiating and fans. In some cases it even went further then just talk. Lets face it, there are coaches, and conferences, out there that promote it so much it comes from the stands now; all in order to drive more fans to see the spectacle and put it on par with other sports. Somehow tennis has a reputation of being a sissy sport, and lacking the confrontational "tough man" appearance of more popular sports like football, baseball, and basketball. Its driven some to try and change this perception by integrating trash talk in the sport, and it even happens on the pro level now. No one understands the sport, so they bring it to their understanding by encouraging this kind of behavior. I fault the coaches on both teams for not recognizing this and stopping it before it got out of hand. They are the ones who should take responsibility for this happening.
Hopefully other players learn from this experience and don't repeat it. I also hope both schools investigate their players and address the issue appropriately.