After running him out, Lyon dropped the ball on a prone De Villiers, hitting him on the chest. He has apologised for the incident.
A he said/she said narrative has since broken out over the change-room spat, with captains Faf du Plessis and Steve Smith disagreeing over whether de Kock was subject to any personal sledging.
"Warner is the type of guy where if things are going well for Australia he's got a big mouth, but when they're losing he doesn't say too much," Harris told AAP.
Read more: Quinton de Kock allegedly made comments about David Warner's wife
"When he says something and someone comes back at him - then he gets upset. That's pretty much all the characteristics of a bully.
"There's always a common denominator in these sort of things and it seems to be Warner.
"Speaking to a few of the players, they really don't give a s**t about what he says. They're just like, well he's quite personal so we're going to come back at him and see how he takes it.
"I know Quinton de Kock quite well and he won't take things lying down. If someone's having a crack at him, he'll have a go back."
Harris, who featured in 37 Tests and was part of the first post-apartheid South African squad to win a Test series in Australia, never played against Warner.
But he noted former teammates are well aware of the aggressive opener's conduct.
Read more: Jeff Crowe in middle of cricket sledging drama
"I know, speaking to a couple of the guys, that he does tend to get quite personal with the way he abuses players," Harris said.
"I've heard from South African players that he can sometimes be quite personal ... if you're going to do that you must be able to take it back, and it doesn't look like he takes it back to well.
"The South Africans haven't moaned about it at all during the Test."
Harris was full of praise for the way Australia played at Kingsmead, saying Mitchell Starc's reverse-swing masterclass should be in the headlines rather than Warner's rampage.
"It's a bit of a dampener on the fact they played such good cricket," he said.
Falzon was in the news back in 2007 when she was caught on film having a tryst in a men's toilet cubicle at Sydney's Clovelly Hotel with All Blacks star Sonny Bill Williams. At the time, Williams was playing for NRL team the Bulldogs and Falzon was the girlfriend of Western Force halfback Matt Henjak.
- AAP