No, they don't own the concept. They own their specific implementation, and the name Wordle. (So you can't name it "MathWordle" for instance)

Or, they could always threat. But only way they'd win is if it's a straight clone (graphics and all), and/or uses the Wordle name to piggyback on that.

Just see how many match-three games there are. The concept anyone can use, don't name your game candy crush and you're fine.