"My impression was that they were sick. Then 15 minutes later they said it was the captain. All the communication was that the pilot was 'sick' or 'not in the condition to fly'. Later, when I spoke to airline staff, they told me the pilot had eaten something bad.
"That was a clear lie."
On Twitter, Muteki wrote: "Care to explain why your captain (i.e most experienced person on the aircraft) waits until boarding time to decide they're too ill/drunk to fly?"
Singapore Airlines spokesman Karl Schubert confirmed the flight had been cancelled because "an operating crew member was deemed unfit to fly".
"Civil Aviation Safety Authority officials undertook a random drug and alcohol test of all crew prior to them starting their pre-flight checks," Mr Schubert said.
"The pilot in question did not pass the test due to having a higher than suitable blood alcohol limit. The pilot in question was stood down and has been suspended from all duties effective immediately.
"He has returned to Singapore where a full investigation will be undertaken. We will also work closely with the Australian and Singaporean authorities to ensure they are supplied the information they require."
Muteki had intended to fly to Wellington for the All Blacks clash against South Africa. He begged airline staff to book him on another flight on Saturday, and even offered to pay more.
He spent the night at an airport hotel and said he was "gutted". But he also said he was relieved at the near miss.
"It's actually really scary. It's a large aircraft. I spoke to others before the second flight and we were all pretty happy we didn't fly.
"Who knows what would've happened."
Passengers who weren't able to fly on Saturday were booked on another flight on Sunday. They were offered a breakfast voucher but Muteki said a lunch voucher at an airport hotel was not honoured because the hotel ran out of food.
Saturday's drama follows claims Singapore Airlines staff were rude to passengers on a delayed flight in June.
SQ516 from Singapore to Kolkata experienced technical issues on June 8 and was delayed for almost three hours.
Passenger Chandni Doulatramani posted to Facebook a claim that she and other passengers were treated badly by staff.
She shared a video showing passengers becoming increasingly frustrated at the delay and leaving their seats despite being told to stay seated.
"When we confronted the cabin crew, they had no answers, rudely shut us up, threatened to call the cops to arrest us, and said, 'We are in the same situation as you are, don't ask us, we don't know anything'," she said.
