Does look a bit odd doesn't it? Probably supposed to be GL_NEAREST_MIPMAP_LINEAR or GL_LINEAR_MIPMAP_NEAREST for the first one (ie. when the antialised flag is true), but it might be that the mip-mapping in older chipsets was slow and it was best to just use NEAREST mapping when mip-maps are in use (pure speculation on my behalf, but I know some older PC GPUs slowed down with full 'tri-linear' mip-mapping (bi-linear mapping on each of the two nearest mip-maps and then blending between those based on how far from each level the sample was)).
Regardless, it could do with a comment - but it is only in the path where the setAntialiased is called, which in the version of code I checked is 3 places - EffectRenderer, RenderTexture and TiledMapLayer, all of which turn the flag off.
Some information on what that flag is about would be nice too - the documentation is the always helpful:
/** True if antialised. */