Sorry to hear about your accident! We would need to know about your ride (SHO/XSport/Flex...) before being able to comment specifically. True, you could end up hydrolocking your engine if indeed fuel has dumped into the cylinders. Would be one of the worse case scenarios. Scoping the cylinders would be the right thing to do there to verify.
However, if you have tuned/meth'd your ride, and the dealership is inexperienced with this kind of stuff, they will tell you all kinds of things just because they don't understand it. So, not to worry just yet.