Actually, I'd be more afraid of putting liquid into a non-running compressor.
A running compressor is generating heat which would help to evaporate any stray liquid that makes it that far.
As I stated before, I charge liquid almost exclusively (except for very small critically charged systems) and have not damaged a compressor this way.
A little care taken to meter the refrigerant into the system goes a long way.
Either that, or you have a LOT of wasted time on your hands waiting for a 50 of 22 to boil off. I'm not that patient.
There are also devices available to do it for you. I also use these for charging azeotropes in the same small, critically charged systems where I cannot charge with vapor and need precise control over the amount of refrigerant used.