I'm sorry, but I think that is extremely bad advice, especially for an INDOOR plant as this one is specified. Malathion is an organophosphate, a class of insecticides that were originally developed as neurotoxins for chemical warfare. Yes, it has relatively low human toxicity and has been used for wide scale spraying. However, here's what wiki has to say:
Malathion itself is of low toxicity; however, absorption or ingestion into the human body readily results in its metabolism to malaoxon, which is substantially more toxic. In studies of the effects of long-term exposure to oral ingestion of malaoxon in rats, malaoxon has been shown to be 61 times more toxic than malathion. ... If malathion is used in an indoor, or other poorly ventilated environment
, it can seriously poison the occupants living or working in this environment. in jurisdictions which spray malathion for pest control, it is often recommended to keep windows closed and air conditioners turned off while spraying is taking place, in an attempt to minimize entry of malathion into the closed environment of residential homes.
Besides some risk to humans, especially in enclosed spaces: Malathion is slightly toxic to mammals, moderately toxic to birds, and highly toxic to aquatic organisms, both freshwater and estuarine, as well as bees (#EPA 2006, #PPDB 2011). https://www.toxipedia.org/display/toxipedia/Malathion
Given the current crisis in honeybees, it is well to avoid use of products that are toxic to them.
And note that the pest in this case is most likely slugs and they are impervious to insecticides. So you would be taking all these risks and accomplishing nothing, if in fact it is slugs chewing your peppers. Slugs are in fact the only things that ever bother my pepper plants.