Well personally I don't see either Andrews or Ismay as being guilty. I mean honestly no one knows how they will react when you're in a desperate situation. Yes they both made mistakes but nobody's perfect.

I think the reason Ismay was seen as a coward all goes back to the media. At the time it probably didn't look too good for Ismay to have lived. The captain went down as did Andrews and many others. So it doesn't look to great to the media when Ismay comes back alive. The media is very manipulative. We see that still today. I don't see either of them as guilty for anything. Ismay did what would be considered natural human instinct, to live.