Bearfoil - Many ADs make reference to possible outcomes to justify their application. The spline wear AD refers to excessive axial movement leading to possible non containment. This is what could happen if the AD is not accomplished.
The reverse is not necessarily true. Hence a non contained IP turbine will not inevitably be caused by a spline problem.
And speaking of splines, do we all realise that the fancy parabolic splines are a GE patent? Reference is made therein to a 1981 RR patent from Bristol, but I can't get my head around it.