John,
You aren't wrong. Research shows that memory is very likely to change or vary, inconstant, and fickle.

This doesn't mean the memories will be incorrect. It means they MAY be and CAN be.

He presupposes that everything is perceived and stored. Hard to say. Maybe. Nevertheless, what I stored is my bias on reality...if it were otherwise we would all respond to stressors the same way.

Always check the trainers credentials and professional background, of course.