My biggest problem with this is the ambiguous "several hours" for all meats mentioned. It's akin to the media useage of "tens of thousands" used to describe 10,001.
Marinades usually consist of three things: oil, acid, and flavorings (spices and/or herbs). The oil impedes oxygen from reaching the surface of the meat (bacteria usually need oxygen to proliferate), the acid helps to kill or limit bacterial growth, and the herbs/spices do nothing but add flavor. If the marinade also includes something alcoholic (which might replace the oil and acid) - that's just another antimicrobial agent.
Shell fish (shrimp for example) would be cooked by the acid in the marinade in a relatively short time, and if left for "several hours" would not only be cooked (denatured) but would also begin to be digested and turn to mush.
Chicken, although not as delicate as shell fish, would also begin to be digested from prolonged marination ... that happens with chicken marinated in buttermilk in the refrigerator for 18-24 hours.
Beef can safely handle longer marination periods at room temp (4-12 hours).
Again, without knowing what "several" means, the marinade recipe, and the protein involved (beef, chicken, pork, lamb/goat, shell fish) it's really hard to guage what would or would not be safe.
However - shrouded in a cloud of doubt - this cookbook is written and published in the USA and I'm sure the authors, and publishers, would have some concerns about liability if they were promoting unsafe food practices.
Of course - I'm sure you could e-mail them your concerns (their Contact Us
webpage is here
- and they have a toll-free phone number) and they could answer your questions.