I'm pretty sure that you can send anyone on the escort mission back to the Normandy with the survivors and as long as they're loyal, that whole group will make it back alright. So that being said, you could send a 'weaker' character like Mordin or Tali back thus ensuring they won't get killed trying to hold the line.
On MY first playthrough, I lost Jack on the hold the line part because she wasn't loyal to me and I lost the whole crew because I thought it wise to clear the rest of my side missions before going through the Omega relay... bad call. On my second playthrough, everyone made it because I learned from the aforementioned mistakes.
On MY first playthrough, I lost Jack on the hold the line part because she wasn't loyal to me and I lost the whole crew because I thought it wise to clear the rest of my side missions before going through the Omega relay... bad call. On my second playthrough, everyone made it because I learned from the aforementioned mistakes.