Rules Team is working on the decision regarding this.
To clarify, they are reviewing only the interaction with A Slight Modification and Thunder Boy/Mario Crane XP and whether or not a reversal will be issued.
Currently, A Slight Modification does not stop these abilities because it cancels the whole text, which allows for the ability to be used again since it is a Repeat Shootout/Resolution.
The decision will be rendered after GenCon in a compendium update that will also include the prevention trumping cannot ruling recently made (Retribution and Shield of Faith) thus cleaning up a lot of older threads regarding that subject.
Thank you so much for your patience in this matter and presenting this concern.