The oil will degas when it hits atmosphere. And even if there is a minute amount of refrigerant remaining, it will be much less dangerous than the carcinogens and toxins in waste motor oil, from an internal combustion engine.
I know it will degas to a certain degree. However, a long, long time ago, I had a large quantity of hydraulic oil that had been thoroughly mixed with water. It was a very nice mayonnaise color. It had no rust, so I wanted to see if I could remove the water. I put some of the oil in a thick glass jug, and pulled a heavy vacuum. For a while, the oil boiled as the water was removed, but it eventually reached a point where the vacuum could no longer pull the moisture from the oil, without some other stimulus. Heat, worked, shaking worked, even putting some window screen in the jar worked.
Apples and oranges, you may say, but both situations are exactly the same. The vapor pressure of freon, at room temperature, is well above atmospheric pressure... and the vapor pressure of water, at room temperature, is well above a good vacuum's "pressure".
The $30,000 question is: Is there enough phosgene left after burning in an MF engine, to matter? I don't know that answer. I have seen the result of whiffing the small amount of phosgene that came from a propane fired leak detector that sucked up a bit of freon from a leaking auto airconditioner system.... And we all have seen the posting from the guy that cleaned some steel with brake cleaner, and then caught a snoot full of phosgene when he welded that steel.
Caution, and some further research, may be in order.
-Chuck