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In my opinion this has nothing to do with freon. The problem is of adhesion. You know the stuff you can buy in the hardware store called Great Stuff or some other such name? This is an expandable polyurethane foam. Guess where the idea came from? Play with some of it some time. Squirt a little on your fingers and press them together, than go find some acetone or MEK to unglue them. This stuff is not freon based and is far less superior to the A/B mix they spray the tank with.

The areas where they are losing foam are in the cryogenic repressurization lines which means they are dealing with ambient temperatures on the external side and negative freezing temps only inches away behind the tunnel covers.

I'm not a rocket scientist, I'm a carpenter drinking beer (LOL) but I think I know what I am talking about.

In my opinion this has nothing to do with freon. The problem is of adhesion.

That is just the purpose of the freon from my reading. It improves adhesion of the foam to this type of surface, and within itself.

I also use polyurethane foam; have 2.5 inches of it on my roof, for one thing (minimally expanding). No problem getting it to adhere there. As you suggest, removing it is more of a problem in construction than application. However, I can easily pull it off the edges of the roof after weathering for five years now, but this is the area that wasn't protected by an epoxy overcoat.