Generally speaking you can file a trademark for whatever you want; you just have to show it is being actively used in the way you say it is being used.

That doesn’t mean the trademark will hold up under a challenge. But a challenge takes time and money, and a recurring theme in this story (and many like it) is that one party is way bigger and richer than the other. For a small business, it’s generally going to be way cheaper to just change their name than to take on a federal court case against a national company backed by private equity—even if they think they would win.