Here's another point of confusion. You say "spinning while moving" when i think you mean "spinning while thrusting." In that case, yes, you'll generate all sorts of weird g-forces. If you are just coasting in space and you spin 180, then the only g-forces is the centrifugal "force" which isn't any different than a similar carnival ride. It doesn't matter how fast you are moving along your linear velocity vector. It WOULD matter if you left your rear facing thrusters on, but then you're not just spinning, you're turning. Some of the confusion might come from thinking in atmo, where, due to lift and drag, planes can't spin without turning.And how does the ability to spin in space relate to the K-turn? The ships don't stop moving during a K-turn, They spin while moving (in the manuever this started from) and that does create g-forces. There is no relevence to the spinning in place you're discussin because there is still motion involved creating some extreme g-forces(that again, the pilot will not get any significant percentage of because space magic tech.)
My confusion comes from why that's a relevent point. Yes they can. But it isn't relevent to combat, or the way a K-turn works/looks.