Well given the damage
the seperation systems might have been offline
The impulse engines of he saucer section might have bee non operable
As they were managing the containment from the bridge, if the were able to sperate and fire up the impulse they might not have been able to put enough distance before the core went critical.
None of those strike me as reasons not to try it. As for the Warp Core explosion? I don't see how that could be any worse than Generations... at least there weren't any planets for them to crash into.