Samlley said that order to accommodate Campbell, current Checkpoint host Mary Wilson would be taken off air, leaving Susie Ferguson, who co-hosts Morning Report on Radio New Zealand with Espiner as the only female voice on prime time radio.
Radio New Zealand has said it has promoted Wilson to a senior news role.
Smalley wrote today: "My position on Friday - and it's the same position today - is that New Zealand society isn't straight, white and male. So prime time radio, which achieves the greatest audiences, should not be straight, white and male either."
When approached by the Herald, Henry said he wouldn't be commenting on the issue. Espiner said: "It's not a debate I've instigated or one I can add much beyond what others are saying."
Campbell, Garner, Hosking and Williams have yet to respond to requests for comment from the Herald.
However, Smalley's latest comments have reignited debate on Twitter - where opinions are still divided on the matter.
Richard Beauchamp thanked Smalley for raising the issue and wrote, "The evidence suggests a need for balance, and balanced argument".
Perfect Mike Hosking, Twitter's popular Mike Hosking parody account, rejected Smalley's opinion that he represented a lack of diversity, as "I drink Pinots from all round the world."
Diversity and inclusion specialists Rainbow Tick also supported Smalley's comments, tweeting "Excellent comments on the need for true diversity - we all win when we're all heard."
Others agreed with Smalley generally, but denied that John Campbell was part of the problem.
"Smalley was fine with agenda being dominated by her extreme right-wing male cohorts. Campbell DOES bring the balance," @mattedwords wrote.
Kim Potter agreed, tweeting that John Campbell was "one of the finer men in broadcasting" but Smalley had a good point - although he added: "Perhaps focus on Hosking/Henry?"
Graham Cameron tweeted: "Fellow men, liking @JohnJCampbell doesn't mean @Rachel_Smalley's wrong. He's a great reporter & the system's a patriarchy; not hard to grasp".
Despite criticism, Smalley said she wouldn't budge from her position on diversity in news.
"I know it made people uncomfortable, but I'm going to say it again. Diversity in prime time is fundamental. No one wins if our world is being shaped by the perspective of one gender and one race, irrespective of their politics."
- nzherald.co.nz