Looking it up online, it's a first level adventure. The PCs have nothing but starting gear to lose and haven't done anything yet - they barely exist beyond backstory. Where's the attachment coming from that it matters if they die? Re-use the same character sheet and have Bob the Fighter #2 wash ashore next round. Done. Alas poor Bob #1, we didn't know ye.
This isn't arbitrarily wrecking an experienced party with assets that really matter and the possible ability to avoid a wreck altogether. This is a party of newbies straight out of CharGen with no stakes in the game and if the GM says they just survived a shipwreck they're already ahead of all the drowned men in the surf. Moreover, the PCs probably have immediate access to better gear and loot than what they own right on the beach with them, left behind by the wreck.
And given their expected level just how dangerous are these attackers? Are we talking hungry crabs nibbling on toes? Opportunistic castaway looters trying to make sure they get to keep the loot? Random scut-quality undead? Is the threat really immediate, serious, and fast enough to prevent the PCs from just grabbing some stuff on the way out and legging it if they don't want to even try defending themselves?
I could see some classes being much worse off than others initially - some casters are going to be frantic about their spellbooks or other gewgaws, for ex, while martials can just pick up a broken plank and go clubbing - but was this opening situation really so badly balanced that there was no chance of survival, or more likely victory and immediate gear upgrades? Really doubt it, somehow. Paizo not usually that bad at low-level stuff.
Going by info provided, the problem isn't the opening, it's the players not trusting the GM to avoid putting them in a hopeless situation before they've made any choices at all. I'd have let them walk and told them good riddance if I were you.