I just got off the phone with Pelican cases in the USA (310) 326-4700 and they said the same thing I did. If the foam is not PINK in color IT IS NOT ANTISTATIC! and it is a special order item. So if your using a case that has GREY foam you can screw up your mics. I am not saying you will screw up your mics but its a chance you take when using regular foam.
A simple test would be take the foam out and rub it against your hair if your hair clings to it its holding a charge, that charge can discharge into your mic capsules and destroy the mics preamp Fet. Or even alter the charge on the mic capsule it self. Ether way I would not trust my $1000.00 mics to foam that was not antistatic.
Antistatic foam has a conductive surface that retards the materials ability to hold a charge in the first place thats why Its so expensive because the conductive but flexible foam is very expensive.