He wasn’t a coward
While the movie did show Cal using a child in order to get on board a lifeboat, there was another story that didn’t make it into the film itself but was widely rumored after the Titanic sank.
It says the White Star Line chairman, Bruce Ismay, had masqueraded as a woman in order to sneak into one of the lifeboats. In the movie, we see him taking a spot along with women and children on one of the boats. But in real life, he helped many other passengers before finding a place for himself on the last lifeboat.