I did a deep dive on it and there are definitely racist cartoons by Seuss, but I didn't find any direct references to his books. That doesn't stop the narrative that there are "strong racist undertones" in ALL of the Seuss books, which seemed to be the theme from most of the articles on the topic. I have to say in 17 years of reading those books to my kids, I haven't noticed them, but I am a 45 year old white guy so I am probably not as sensitive to them.
Should we boycott ABC / ESPN / Disney because of Song of the South? A movie that still had a ride (Splash Mountain - Magic Kingdom) associated with it up until a few months ago. I have known that was racist and told my daughters as much for years now every time we rode that ride. Shocked it has lasted as long as it did.
I understand the point of view of the students and athletes. I think (hope) that the school is taking the right approach. There are also plenty of people that identify with the song and have emotional ties to it for numerous reasons, none of which are (likely) racist. If we start eliminating everything in our culture because we can 6 degrees of Kevin Bacon our way to a racist history or attachment, there won't be much history or culture left in this country. This country has a racist past. In some ways, I think identifying and using items that point to that history to educate and understand is better than eliminating and deepening the divide.