I sometimes add a little sodium chloride in the form of sea salt, to my water. My thought is that it might accentuate the flavor. I don’t add a teaspoon, just a pinch.
My quick calc shows he added 145ppm if a tsp is 10g. that stuff is fairly fluffy, maybe it was only 100ppm. i think it will be fine. But I haven’t heard of adding bicarb to mashout water before so I’m curious.