The cause of food borne botulism is NOT the bacillus itself, but the exotoxin that it produces as a by-product of its microbial metabolism.
The organism Clostridium botulinum probably won't compete real well with normal intestinal flora for real-estate to colonize nor for available nutrients. I'm NOT saying that it can't happen even if a person is not immunocompromised in some fashion or has not been on broad spectrum antibiotics that have reduced normal intestinal flora, but onset of the symptoms of Botulism can be as short as 4-5 hrs (IIRC) after ingesting just a fraction of a microgram of toxin. Given the time for (possible) spore formation, passage through the digestive system so that the toxin can be absorbed into the blood stream, (possible) spore germination, successfully competing for real-estate and nutrients and reproduction (at most one reproductive generation every 20 min in the human body), that could be cutting it real close for the organism itself to be the problem - i.e. growing and producing sufficient toxin in vivo, instead of the toxin itself being directly ingested. In a nutshell, the toxin itself generally needs to be ingested (wounds excepting - read on...).
In wounds, it is again the toxin, though the bacteria does not have to compete with other normal flora (a wound doesn't have any "normal" flora) for real-estate and nutrients - just the body's infection fighting mechanisms. Even in these cases it is the toxin that migrates via the blood to other parts of the body and there performs its possibly deadly work.
Fortunately, the exotoxin produced by C. botulinum is thermolabile and is easily denatured by heat. Even simmering (soups, etc. - i'm not sure of how long to roast) over a low heat for 10min (to be safe; even though incidence is low, mortality rates from botulism poisoning are high - why take a chance?) should do the trick.
Keep in mind that ONLY non-acidic foods (e.g., french potato soup - the classic food causing problems since it is sometimes served without heating) offer one of the proper conditions required for growth of C. botulinum. Acidic foods like tomato sauce (tomatoes generally have a pH in the 4.0-4.5 range and so are too acidic to support growth), for instance, are too acidic for C. botulinum to grow. Even potato soup can be heated and then cooled for a short time in a refrigerated environment and then served when it relatively quickly reaches the proper temp.
It is very difficult (relatively speaking) to "kill" C. botulinum and related organisms (C. tetani [the etiological agent/causative organism of tetanus], C. perfringins [the etiological agent of gas gangrene], or its aerobic cousin Bacillus anthracis - causes anthrax) since they form "endospores" when they are exposed to conditions not conducive to their survival (later, upon finding better conditions, the spores germinate and the bacteria start to multiply) that are very heat resistant. Five minutes of active, boiling ("rolling" boil) should be able to kill 98%-100% of these endospores. In a microbiology lab, they go "overboard", viz. 15minutes of super-heated steam (15psi which cause water to boil at 250 deg F) when sterilizing items in a steam autoclave.
BTW, while this was not the subject of the initial Post that mentioned Botulism, members of the genus Clostridium are normally found in the soil, not water. Hence, they are not normally a concern for hikers.