This isn’t correct. If you are using a 174Q crank, you can’t get back to a 52mm chain line, however, if you are running XXSL, it’s available in both 168Q and 174Q and a 168Q crank with a 3mm offset chainring is a 52mm chain line. I’m running that exact setup with a new XXSL crank/threaded PM and an XX1 Eagle RD/cassette.
The spacers for the crank are also dependent on the spindle length. A 168Q XXSL will still take 0mm spacers on non-drive and 4.5mm on drive side.