I think its a pretty clunky interaction, however it does make sense to me.
Security testing says 'The first time you make a successful run on that server this turn, instead of accessing cards, gain 2c'.
Crisium Grid says 'Successful runs on this server are not considered successful or unsuccessful for the purposes of card abilities'
Crisium Grid server is nominated for ST. When it's run, it is a successful run, but not for card abilities. So you don't get your ST money, but you do access cards, and you have made a successful run on this server. If you run it again, it is not the first successful run on this server, so ST doesn't trigger. I guess I would have been happy with the alternative ruling too, but this one is fine.
As an aside, I hadn't noticed until this thread that you can't successfully ST the same server more than once. I really should read the cards more carefully! (I don't think I've tried either, but you never know)