There doesn't need to be a study on pH crashes, because they are pretty well understood today. Here's the basic idea: The end product of the cycle, nitrate, is acidic. The bacteria take a neutral chemical, and make an acidic chemical at the end. That means that acid is constantly being added to the tank, slowly but surely. More acid means lower pH, unless there is a buffering agent. Fortunately for the fish, most water does come with a buffering agent. What a buffering agent does is resist changes in pH. Buffers don't keep the pH constant, but very nearly constant (the mathematics describing how a buffer works is pretty complicated and probably beyond the scope of this post, go check out a good quantitative chemistry book for a fuller description). So, in the case with buffering, when acid is added, a certain amount of buffering agent is consumed to prevent the pH from changing too much. This is what happens in our tanks, the acid from the bacteria reacts with the buffering agent and keeps the pH pretty close to constant. KH, which is the abbreviation for carbonate hardness, is one measure of the acid buffering capability of water (note that it is properly written as both capital letters).
So, a higher KH means that that water is more resistant to changes in pH due to acids, like the acids from the end of the cycle. Your boss was mostly correct, because KH is the most common measure used in fishkeeping to know how resistant a tank is to pH crashes. The dissolved organic chemicals don't play a very large role in pH and buffering at all, though.
However, pH crashes really shouldn't be an issue with a well-maintained tank; where specifically well-maintained means regular significant water changes. This is simply because not only will water changes reduce the concentration of nitrate, and hence the concentration of acid, but also will increase the concentration of the buffering agents. People with water with low buffering will have to do more water changes to keep the buffering up, or add materials that will increase the buffering. Sea shells and mostly calcium rocks help increase buffering, and there are commercial chemicals out there, too. But, the best solution if you have tap water with a decent amount of buffering in the first place, is to do the maintenance you should be doing in the first place.
