Classics rider with one monument? He's a meme, not a legend. I wouldn't rate him over a guy like Cunego.
Ardennes triple I think is just too niche for me to attach much added value to. It's like calling Roglic a legend if he wins Lombardia on Saturday for sweeping the hardest Italian fall classics.
Of course he didn't win enough to be regarded as a legend for that alone, but still being able to do something that hadn't been accomplished in almost 40 years of racing should certainly make people remember him for longer than Cunego.