Cecchin, who disallowed a try that would have given Tonga an upset win, has told The Sydney Morning Herald he was in an Auckland bar when police rang to tell him they had contacted him and several family members that had been targeted.
He was advised not the leave the hotel and told he would be picked up and taken to the airport.
On his return to Australia, he was picked up by the Australian Federal Police.
He also flicked through his phone to discover more than a thousand "vile" attacks, the likes of which he had never encountered across his entire career.
Cecchin, who will referee his 300th NRL game this weekend, said he planned to quit the role soon.
He said he would leave the NRL at season's end over "vile" abuse and mounting pressure on referees.
Cecchin made the decision after not being picked to oversee Origin I this season following a difficult 12 months for the leading referee.
The whistleblower, who has talked openly about his mental health battles, said negative referee "noise" had taken its toll this year and he "needs a long break".
"The reality is that after that game, and for the first chunk of this year with all the noise that's been out there, it's been tough. Really, really tough," he said.