No ones said they are using new parts did they? Was this a legitimate media day ? No was this used as a test day? Yes. Is it illegal? No. Is it dirty? Yes.
Actually, a "media" day is where the team runs there current car on a track to get images and video footage for use in commercials, on websites and for use by sponsors etc. Every team has them, and they all use them. Every team runs their "current" spec car for these days, it's where they can setup up shots and video.
When a team runs an older car (I think 2 or more seasons old) they are effectively getting/using a "free" media day).
I'm pretty sure they took media images and footage that is needed and will be used by the team, their website and sponsors.
There are quite a few images from the day, no measuring equipment, no pit wall, car was parked in the media after running so no measurements there. Special tyres are used for these days so no comparable data can be collected.
Here's a thought, perhaps Ferrari actually went 24 hours with viciously cheating and undermining F1
