"There was nothing that was even close at the time to uphold that it was a legal throw, Stevenson told the Radio Sport Breakfast.
"All of a sudden they decided to look at it again tonight. There may have been some new angles they wanted to throw into the mix with the grand jury but we've had updates that it's all confirmed.
"Basically once the medal presentation done, that's a fair checkpoint to end the proceedings. So barring anything, unless someone has got a secret worm camera embedded in the ring that no one knows about, we're going to celebrate like it's a gold medal and Tom's world champion."
Yesterday second-placed American Joe Kovacs also launched a protest after his final throw of 22.08m was red-flagged.
Walsh won the event with a best throw of 22.03m.
Walsh told the Radio Sport Breakfast that it was a special moment to receive his gold medal.
"It was amazing. I'm not a teary guy, but my eyes may have watered a bit," he said.
Walsh received his gold medal this morning as the New Zealand national anthem was played at the London Olympic Stadium for the first time.
Female shot putter Dane Valerie Adams was denied the chance to hear the New Zealand anthem ring out in 2012 after finishing second behind drug cheat Nadzeya Ostapchuk.
Adams received her medal at a presentation in Auckland a week after the Games.