I think my only real quibble with it is that the author thinks some things will last a lot longer than they really would.
Bear in mind: this is the first book to describe a post-apocalyptic future without Morlocks and Eloi in it. Gasoline was a petroleum distillate with tetraethyl lead, not the postmodern witches' brew we have these days and power generation was a lot less optimized and therefore more stable. When the book was written in 1949, "gasoline" was a newer technology than "fax machines" are today. Shit, when that book was written, fax machines were fifteen years in the future.
Now? Sure, we've got a popular culture sheep-dipped into Dark Tower and Walking Dead and Road Warrior and every other postapocalyptic tale I'm forgetting but Patient Zero is that 70-year-old book that you're quibbling science over.
"In 1974, samples of canned food from the wreck of the Bertrand, a steamboat that sank in the Missouri River in 1865, were tested by the National Food Processors Association. Although appearance, smell and vitamin content had deteriorated, there was no trace of microbial growth and the 109-year-old food was determined to be still safe to eat."