Your intuition about the salt masking the sweetness also might be right. I could understand how salt could masquerade sweetness in a finished crust. Your test should give us an idea if less salt is used in the formulation if the crust becomes sweeter.
This morning, I decided to conduct an experiment independent of the last MM clone dough I made with the Steen's 100% pure cane syrup and the Grandma's Original molasses to see if salt does, in fact, masquerade the sweetness imparted by those products. What prompted the test to begin with was the observation that came to me recently when I reheated leftover slices of two different MM clone pizzas. I didn't note which dough formulations I used for the two slices but one of the slices tasted noticeably saltier than the other, with little perception of sweetness. Up to that point, I had been playing around with salt levels between 1.75% and 2%, but mostly at 2%. That was also before I saw and studied the MM Nutrition Facts.
For the test, I took the formula amounts for the water, the Steen's 100% cane sugar syrup and the Grandma's Original molasses that I used for the most recent dough formulation and I made two identical separate solutions. I stirred the solutions to dissolve everything. I then added the formula amount of salt from the most recent dough formulation to one of the two solutions and stirred the solution to completely dissolve the salt. So, the only difference between the two solutions was that one of them contained salt and the other did not. For my test, I used Morton's table salt, on the assumption that MM might be using a similar salt because of price and the smaller particle size of ordinary table salt that might dissolve more quickly and uniformly than other forms of salt and, accordingly, lend itself better to commercial production. I then tasted the two solutions, rinsing my mouth out with plain water between tastings. After several such taste pairings, the results clearly showed that salt does, indeed, reduce the sensation of sweetness. It was much more than I would have imagined. As an additional simple test, I decided to add oil, in the amount I used in the latest dough formulation, to the two solutions to see if that had any effect on sweetness (which I doubted). I could not detect any impairment of sweetness due to the oil. Of course, the oil did not dissolve in the water, but I stirred it anyway before taking my taste samples.
Knowing that you have been using Morton's Kosher salt, I did one final test in which I placed equal amounts of the formula water from my latest dough formulation into two containers and added Morton's table salt to one container and Morton's Kosher salt to the other, in equal weights. After stirring to dissolve the two salts, I tasted them, again rinsing my mouth with plain water between tastings. After several such taste pairings, I thought that the Morton's Kosher salt solution tasted a bit saltier than the Morton's table salt solution but I don't think that the difference was great enough to really matter.