When I say not to follow the rule in these circumstances that doesn't equal carry on past the point of the person tapping out. It means go no further but don't let go. If anything relax the pressure whilst still holding. This gives the person time to realize nothing has happened yet and the cause of the imagined danger is theirself. Thus they learn. Now you will have really earned their trust.
When they know you know the difference then the trust grows. They know they are in safe hands.
I have seen quite a few characters over the years who suffer from this phenomenon and usually sit back and watch for a while. Let's take nikkyo. A person does nikkyo and this fellow goes down hard or awkwardly with a whelp and nage immediately lets go. The uke complains and blames and nage feels bad and apologetic. Now this fellow moves onto the next partner and a version of what happened before reoccurs. I watch him work his way through the class or find an excuse to stop. Meanwhile there's two or three confused students all now scared to do nikkyo. It's quite amusing.
I now call him and go to apply nikkyo. He's already on the way down and pulling away both. Tapping his leg. My hold is relaxed, my attitude is calm and reassuring, my smile is warm. I point out nothing has happened yet and he relaxes. This opens the door to show him what a good nikkyo is and to show him how to relax in the face of it and then onto how to relax in the face of a not so good one also.
Why didn't you say so in the first place? Yes, this is a reasonable approach to this sort of situation.
Earlier in the thread, you scoffed at someone for using personal experiences to support a point of view. But examples and personal experiences are a lot more concrete than generalities and platitudes.