I don't think anyone meant 'reckless' in the sense that she was reckless running into the tunnel in Autumn Term. But it is a case of Fortune Favours The Brave. The boat could have been smashed on the rocks drowning them all before they got to the beach; yes, Peter and Nicola have accepted that it is better that Foley is stopped even if that means they are killed, especially as they will end up dead anyway if Foley gets to the enemy - even if they haven't yet vocalised that to themselves. I am far from criticising Nicola, I am admiring her because it's people who take those decisive risks who do save the day. But they do need luck to go with them too!