Because there's nothing specific to Intimidating Force that makes it work differently than other counters. It's the general rule for how all counters work, as detailed in the Systems and Use chapter of Path of War, including a sidebar that specifically calls out how they interact with Natural 20s.
Except that those are a very different set of circumstances from the ones the question I answered was asking about, and by conflating the two you confuse the issue instead of clarifying it. It wasn't a question about swapping maneuvers, it was a question about taking maneuvers for the first time at a high enough IL that you had to concern yourself with prerequisites and their restrictions on maneuver choice.