I guess calling him a quitter is unfair. But I guess that separate legitimate heroes and wannabees a bit more. Because you can see that his quirk _can_ be useful if he train it, and in the recent chapters of main manga the lesson is basically "there's no useless quirk, your quirk can be strong or weak depending on your creativity and your training."
I kinda disagree with that, i dont think its the lesson of the last few chapters. To me that seemed more like "strong quirks can initially be a little hard to control"