Portable toilets don't use pipelines to get rid of the waste. Plus, any gas pipes on a construction site by law have to be able to withstand lots of beatings. I should know, since I use these things daily while on the job. Freak accident, nothing more.
What this guy was doing at the site in the first place I don't know. If he was an employee, his contract contains a clause wherein he recognizes the inherent dangers of working in such an environment i.e. can get covered by workman's comp but can't sue. Otherwise, he had no reason being there.
Either way, no basis for a lawsuit. Certainly not worth $10 million in damages.