The $(K^-,K^+)$ $Xi^-$ production inclusive spectrum is reinvestigated in view of the very weak $Xi$-nucleus potential predicted by microscopic calculations with the SU$_6$ quark-model baryon-baryon interaction. The inclusive spectrum is evaluated by the semiclassical distorted wave (SCDW) method. The explicit comparison of the strength function with that of the Green-function method demonstrates the quantitative reliability of the SCDW approximation. It is presumed that the presently available data at the $Xi$ production threshold region does not necessarily imply the attractive strength of about 15 MeV for the $Xi$-nucleus potential in a conventional Woods-Saxon form. Instead, an almost zero potential is preferable.