Not exactly. Protein does not cause bloat (excess amino acids are simply excreted - even by herbivores) - and most authorities on this subject now agree that it's intestinal flaggelates that typically cause "bloat" conditions, not bacteria.
I think that it's important to understand that "bloat" is a symptom of a disease, not a disease on its own. Intestinal flagellates are common in most freshwater species, and typically these intestinal parasites will not have any serious affect on their host. But, place that same fish under enough stress, enough to weaken its immune system, and within the blink of an eye those same parasites can multiply to numbers that the fish simply can't cope with. If/when those numbers reach epidemic proportions, they can & often will block the intestinal tract of a fish eventually creating what is commonly referred to as "bloat".
Having said that, overfeeding (such as in this case) can on its own cause blockage, and constipation, and the end result is also a "bloat" like condition. This is precisely why in this situation I recommended epsom salt. (as a purgative) When fish come down with parasitic bloat, medication such as metronidazole is required, adding epsom salt to the tank water will have little effect on intestinal parasites.
HTH