I am of the opinion if the Shabbos App is true and not a hoax, the backers are trying to minimize the Chilul shabbos of those who keep “half Shabbos” as opposed to trying to get more people to text on Shabbos.
Its like if someone is driving on shabbos and asks you directions, you are supposed to tell them the shortest route to get there in order to minize their chilul shabbos