There were many things you could've chosen to do after making the shapeshifter very suspiciously laugh. Run, mark them with something that can't be removed by shapeshifting, steal evidence, RUN.
A basic attack is not what I would consider....wise.
She passed the intuition check on if he was a shapeshifter, but not the check on if she should confront him. Why does everyone oust shapeshifters instead of playing along until they're in an advantageous position?