The problem in question appears when trying to run a BGE runtime with command-line options - in this case, to disable mip-mapping. This has been tested by other users of the Blender community, who had the same results I did - command-line options work in GLSL mode, but not in Multi-texture mode.
I ran across this bug while making a script to restart a BGE runtime with mip-mapping disabled from an in-game scene (a preloader).
To reproduce the bug, make sure the visible scene is the Preloader scene, and export a run-time in Multi-texture mode. You'll note that mip-mapping is not disabled on the cube that appears (and so, the texture is blurry). If you export another runtime, but this time in GLSL mode, the cube has no mip-mapping applied (and so, the texture appears sharp).
This appears to be a problem with the BlenderPlayer, not the script.