Even the 'one hand rule' wouldn't have saved Mike from a nasty burn as his hand must have made contact with two nearby points at different potentials. Furthermore, using an isolation transformer negates the ability of an RCD to detect earth leakage. After all this an RCD feature which can and does save lives.
I'd recommend this article by Rod Elliott of ESP to anyone who might be unfamiliar with the pros and cons of using an isolation transformer:
http://sound.whsites.net/articles/iso-xfmr.htm
Alan