If you read the article, they mention how some of the threats are coming from other countries. So while some of it may be dumbass racists thinking they’re achieving something, a good amount of it just comes down to foreign powers sowing discord and election interference. Calling in a bomb threat related to a politically divisive topic is a pretty low effort thing to do if you’re a rival superpower.
True and I certainly don’t doubt that there are plenty of idiots at home who think that calling in a bomb threat to a school will accomplish something. But it’s also very easy to call in a bomb threat and for a politically charged situation like this, it would be a no brainer for a foreign state actor to take advantage of the situation. It costs them next to nothing and further fuels the political divide within.
If there’s dozens of bomb threats being made to the same schools, I would more surprised to find out that rival superpowers aren’t behind at least one or two.