"While I considered Oki's comment, I also understood we had to go through a commissioning phase with the hydro machinery, and that would extend out gradually before we were in full production mode," Mr Mason said.
"Up until the time of the explosion, we weren't really in full production mode."
Earlier, two lawyers for the mine managers said Mr Nishioka, who left Pike River Mine a month before the disaster warning that it could explode, had offered to return.
Mr Nishioka was brought in to commission hydro mining but walked off the job a month before the November 19 blast.
The royal commission heard that he arrived in July, and by October, as his contract ended, methane levels had soared and the fans kept failing.
"I left the mine because I felt the mine would explode at any time," he said.
But John Haigh QC, lawyer for mine manager Doug White, suggested Mr Nishioka also left because he had a new job to go to in Saudi Arabia, and had told mine manager Doug White that he might be available again when he returned from Saudi Arabia.
- Greymouth Star