salt will have no effect on the concentration of nitrite in your water. It temporarily reduces the effect of nitrite toxicity used about at 0.1-0.3 % -- the chloride ion counteracting the nitrogen blockage of oxygen uptake.
The salt is bad for the bacteria that eats up the nitrite and makes the conversion to nitrate. Your conversion will slow, more nitrites fewer nitrates.
Salt, sodium chloride, NaCl, at the levels used to block nitite toxicity (less than 1 teaspoon per measured gallon water volume) has no, repeat no detrimental effect of nitrification bacteria.