Can you explain why mag/citrate (CALM) helps build biofilm, whereas glycinate or oil does not?

Magnesium does not directly cause biofilm. Magnesium is a necessary nutrient and one in very short supply the oh-so-SAD (Standard American Diet). Magnesium is used, along with other components, by pathogens to build biofilm. This fact formed part of the basis for the anti-magnesium stearate lubricant used in the supplement industry. If you are eating good foods, you have magnesium in your diet. If you threaten pathogens, they will 'quorum sense' and decide to build a protective fort, (i.e. – biofilm). So if you are threatening pathogens, they'll look for Magnesium (and calcium, iron, and polysaccharides). In this plan, the botanicals have anti-quorum-sensing components that help prevent pathogens from responding with fort-building activity. That's one of the reasons that the short 3-week timeframe can yield respectable results. Hit 'em hard (which is indeed a threat), and don't let them have a town meeting and decide to build a fort. But don't engage a "witch hunt" about magnesium. It's a most valuable nutrient and serves your entire body. More germane to your question, magnesium oil is absorbed via the skin, so it does not enter the GI tract where a pathogen might use it as a resource.