You would have to shift LESS weight to correct a tail heavy condition at a 100mm location than at the 90mm location (fulcrum point).

You are confusing moving the pivot point (in this case from 100mm forward to 90mm) WITH actually moving the CG.

If you have a tail heavy condition at 100mm, then slide your fingers forward to the 90mm location (pivot point) and lift the plane again, the tail heavy condition worsens!

Confused? Me too...Hope I got this right!