Since when is a dive to 120 ft. necessarily a technical dive. Maybe for your organization but for many this is a simple dive to a wreck on a large single and a pony.Here is a prefect example of thread shift. The original question was "recreational" diving. Diving a wreck in 120 is a technical dive. Add to that "forgetting" to swap to a new tank AND never looking at his pressure gauge until he runs out of gas is beyond stupid and a pony bottle wont fix stupid.
It would be interesting to know the size of the cylinder he was using....just of giggles.