Preserved garlic is famous as a source of Botulism. It’s packed in oil, so bacteria can survive in the anaerobic environment. But, so is my peanut butter - it separates until all the peanut material is submerged under a layer of oil. How come we never hear of this as a source of botulism?
Roasting peanuts would kill any spores. Garlic is raw and unprocessed.
No idea about raw peanuts used for PB.
My guess is the water activity is too low in PB, but not in the garlic clove.
I found this:
In the 1980s, health officials traced several outbreaks of food-borne botulism to improperly stored garlic in oil. Mixing garlic with oil cuts off the air supply to the garlic, creating the anaerobic conditions that botulinum spores love. After the outbreaks, the U.S. Food and Drug Administration required food processors to add acids to garlic-oil blends to inhibit the growth of bacteria.
SOURCE: Eating Raw Garlic & Botulism
So, I would assume most store bought garlic that is packed in oil conforms to these regulations. If you chop and store your own garlic like this then you need to be extra careful to follow food safety procedures. Botulism is one of the most dangerous things on the planet (that is not hyperbole).
Fresh garlic (the papery bulb you get in the store) is no worry since it is exposed to oxygen.
Considering how widely garlic is used in cooking and how few cases of botulism we hear of in the US I don’t think there is much worry unless you are doing this at home.
As for peanuts I think they are roasted before making peanut butter. The roasting kills any botulism that might be present.
That is a guess on my part though.
I’ve bought fresh garlic all my life. This is the first time I’ve ever heard of this. 
Whew.
ETA: I dropped in here because my wife sometimes makes her own peanut butter to make sure all the ingredients are fresh and healthy. I’m glad to hear that there is no way roasted peanuts can become deadly in peanut butter.
Botulism is pretty rare but it is also super deadly.
If you buy fresh garlic you are probably fine (so, so many bulbs of garlic are sold and we never hear of botulism poisoning).
If you or your wife store garlic in oil or some other oxygen free environment then you need to be very vigilant about food safety.
That said I don’t know why anyone would bother. Garlic bulbs can last many weeks on a shelf in your cupboard just fine and they are really cheap to buy and in most cases are better in a recipe than the jarred stuff.
If the roasted peanuts are then exposed to air, they can still get botulism spores in them. Unless the jar is pasteurized after filling.
That’s not an issue unless they grow. In which case that’s a question of temperature, pH, salinity, water activity.
It’s not to store the garlic, it’s to make garlic-infused olive oil. Which you shouldn’t do.
I’ve also seen large olives that have been stuffed with garlic cloves in both brine and oil packed versions. The brine versions, no harm - no foul. Pretty tasty too if you don’t mind breath that can strip paint. The oil packed ones scared me though. I’m hoping the preserving process worked but I was not going to find out the hard way.