A section of flex hose sounds like a good idea on the end of a stiff one to make life easier for the user. HVLP spray guns running off a turbine have obnoxious thick awkward hoses so this concept is common there. Look at the Fuji. I've seen lengths of "whip hose" for sale from air hose vendors, but it doesn't mean anti whip as in flailing around, it means whippy as in more flexible.
I'm not convinced about the whip check argument. QR fittings have the advantage that they can swivel. Surely a threaded connection under repeated vibration is as likely to unscrew as a QR is to shake loose ? There are some very high quality QR connectors out there if you pay for them.
Incidentally, if you work with serious high pressure hose in hydraulics, water pressure testing etc. A "whip check" is a flex steel wire usually with spring closure nooses at both ends. This is fitted to the ends of two hoses being joined together. In case the joint fails, it stops the hose end flailing uncontrollably and killing someone.