Switching circuits are "interesting" because the ground
bounce can be greater than a forward diode drop, allowing
that to get into places it shouldn't (like your analog loop, Vref
might not be helped by charge pumping).
You may have to stack diodes to allow yourself some room
for some amount of bounce, because you won't get to zero.
Quantifying the likely amount of it on a well-designed board
in the end application, might be good to try (though not to
entirely believe).
You can simulate ESD breakdowns if you bother to take the
data and fit it up. I do it. But maybe your foundry doesn't.
Mine neither, which is why I bother. You can design ESD
protection pretty well if you go at it methodically.