Could've been a temporary supply. Don't remember the caterer unfortunately. However, it was pretty good (though that doesn't prove frozen versus fresh)
I'm telling you that ex-IST, I've had meat KSML (in Y). I know OP was asking about C, so I was surprised that they have meat for Y but only dairy for C.
Then that must have been a long time ago, or a temporary supply (eg longlife due to shabbat). The regular kosher meals from IST in both Y and C are milk and fish only.
Is it served on proper china? Proper portion? Or is it Stogel style?