One doesn't need to play piano at all to write a piece of music, especially these days with the assistance of music software capable of playback and easy manipulation at the composers discretion.
If that is the case, or if they play but write beyond their technical abilities, I'm not really bothered by it. In fact, I usually listen to them anyway out of curiosity. This being a piano forum, however, doing the same for non-piano compositions may seem out of place; then again, it's not typically something that will ruin my day.