If you're going on that eastwards crossing across the northern Atlantic at the start of hurricane season, averaging two gales at sea per crossing, by all means, do screw the floorboards back down for the trip if it makes you feel better, it's only a couple screws. Otherwise, I can't say we've ever been worried about a knockdown, and we have ended up in some nasty weather on occasion.
And in case you're still concerned what would happen in a knockdown, have a look around the boat and think it through. I'd be much more worried about the fridge lid flying off or the massive solid mahogany companion way steps anyways. Or the underseat/bed lockers with all their heavy stuff in it. Or just about anything else on a fully laden cruising boat. I'm not sure the locker latches are strong enough to hold heavy tools or bottles banging on them from the inside, I'm not even sure the tanks are well enough attached not to come loose. So the floorboards would make little difference to the ensuing chaos, I think
Don't tell your sailing companion about that though, or you'll never be allowed to leave the Solent