Its hard coded into Poser. IK chains with the internal name of "rightLeg" and "leftLeg" are turned on by default when the figure is loaded. The solution is to edit the names in the CR2 file. In a text editor search for "inkyChain rightLeg" and change it to "inkyChain right-Leg". Below it you'll see an "on" flag that you can change to "off". Its not changing the flag that makes the difference, its changing the internal name. The flag is now just a working option, not one that is going to be overridden by Poser.

Repeat for the left leg.