"The long cooking process sterilizes the food"
This isn't true. While extended periods of cooking definitely kill off most pathogenic bacteria, there is no way to truly sterilize a food at the low temperatures you're dealing with using an immersion circulator. The best you can hope for is pasteurization. There are a lot of bacteria that produce vegetative spores, which, even after a long cook in a sous vide set up, are still viable to grow.
"vacuum sealed pack leaves no ability for microbes to re-infect the sterilized foodstuff"
This also isn't true. Vacuum packs or no, there are bacteria that, if present or their spores are present will grow in an oxygenated environment or an anaerobic environment. Many of the pathogenic bacteria responsible for food borne illness will happily grow in a vacuum packed environment.
Even if you've cooked something for a long time, even if it's been vacuum packed, you still need to observe basic food safety. If you're not going to eat it right away, you need to get it down out of the microbial "danger zone" as soon as possible, because if there were spores present, they will have survived, and the food you cooked was not highly acidic, they will begin to germinate, produce bacterial cells, and begin multiplying.