A professional chemist? A professional chemist wouldn't just throw something out like that if they are not experts in food chemistry (it is a separate specialty). As a rule in chemistry heating speeds up reactions, but it is not needed for every reaction, and many reactants degrade with heat, or the reaction is exothermic and you need to actually cool it down (e.g., if you dissolve NaOH in water it can heat up to boiling point and needs to be done on ice otherwise the beaker/bottle becomes too hot to touch). None of the ingredients we work with are that reactive though. Unless that chemist knows and has written out every single compound in every flavour in a recipe, and thought about how they could react with each other they shouldn't just say "heat it up". I am a biochemist by training but can't speak about mixing, what I can say is that pretty much every mixer I follow says that: a) you shouldn't froth because it introduces too much air in the mix, accelerating oxidation of nicotine and peppery taste. b) you shouldn't heat because it degrades flavours c) you shouldn't breathe liquids made with 2019 ingredients as they simply don't need it, and you may risk losing some finer volatiles d) there is no speed steeping, ingredients and time is all that matters.