In a high pH developer like Rodinal which is essentially non-solvent to begin with I can't see how adding 30g/L NaCl would provoke dichroic fog.
If NaCl in this concentration acts as silver solvent there is a chance it produces dichroic fog. At least the common narrative goes that Microdol introduced 30 g/l NaCl, then, as newer emulsions hit the market, suffered from dichroic fog and that Microdol X was introduced that had an extra agent to prevent this. There is a Kodak/Henn patent for Benzophenone, albeit with other developers (which doesn't say a thing about the real reason Kodak patented this compound).
Chances are that newer emulsions don't have this problem anyway, so it comes at no surprise that Patrick Robert James never ran into it so far.
Trying to be the best of whatever I am, even if what I am is no good.
It was only Kodak's US emulsions that changed and suffered badly from Dichroic fog with Dk-20 and Microdol. In the UK the Kodak Ltd, Harrow, new films were fine and they continued selling Microdol for longer before switching to Microdol-x.