You don't get condensation when you put the Phantom IN the fridge. It's when you take the cold phantom OUT of the fridge that you start building up condensation due to the cold internals sweating. Think of the outside of a glass of ice water sitting out on a table.
So the bag thing does you no good if you take the phantom out of the bag once you take it out of the fridge. Leave it in the bag once it's out of the fridge, or don't even bother. Personally, I wouldn't even mess with any fridge stuff. Not really necessary.
Why would you make such a series of comments having no idea about someone else's location, climate, or particular circumstances?
There are many comments in this forum about the need to do IMU-calibrations while the units are very cold.
We've all read that before doing their calibrations, several folks place their P3's under air-conditioning vents, out on chilly patios overnight, or in their cold basements. Since I don't have any of those, I use my refrigerator for a half hour, which works FLAWLESSLY for me every single time. If I don't use the fridge, I get 5-10 minutes of battery-draining warm-up-times before each day's flying.
As far as the plastic-bag, as a decades-long expert snow skier and outdoor photographer, I am quite familiar with how and when changes in temperature cause condensation – and therefore, always put my good camera and mobile phone in sealed sandwich bags before coming indoors from skiing, until the condensation dissipates.
I do agree with you that, since a refrigerator is above freezing, it might not be necessary. But it can't hurt, either. Putting the bag around the P3 before the it goes into the fridge ensures it doesn't get moist when it comes out. The bag comes off in a minute or two, before the unit warms up too much.
As I mentioned above, all of this works flawlessly for me, in my particular circumstances, every single time. Obvious, you and everyone else should do what works best for you!!
I've never had a bad flight! I hope you're enjoying yours as much as I am! Happy flying!!