Constitution writer Jade Donavanik said he would proceed with the proposal to ban members of the "five rivers" from politics for two years.
Prime Minister Prayut Chan-o-cha said on Thursday he did not agree with the idea and suggested the constitution drafters stick to the 2014 interim constitution as guidelines.
He did not spell out the provision in question but the charter bans from politics members of the Constitution Drafting Committee (CDC) after the highest law it is drafting takes effect.
There is no such ban in the interim charter for the remaining four bodies set up by the junta — the National Council for Peace and Order (NCPO), the National Legislative Assembly (NLA), the National Reform Council (NRC) and the cabinet.
"That the NCPO's leader disagrees with the ban and urges adherence to the interim constitution is understandable since that charter was written under the NCPO," said Mr Jade.
"The proposal shouldn't hurt anyone's feelings, especially if he understands he's serving the country during the transition period and will have to hand over the reins to others when the time comes.
"I'm not disappointed. I thought it through before I came up with the proposal but if the majority [of the CDC] disagrees with it, it's okay," he said.
Mr Jade, the dean of the graduate school of law at Bangkok's Siam University, unveiled the proposal on Wednesday and has since been bombarded with criticism from members of the five bodies.
Even those perceived to be on the opposite side of the political arena are not thrilled either but for different reasons.
Chaturon Chaisaeng, a Pheu Thai MP, wrote on his Facebook on Friday he did not think all members of the five rivers would need to take a break from all offices.
"They should be allowed to run for MP seats. If they are elected, they can be ministers. It doesn't matter whether the [new] charter is being written in a way that favours some parties or groups: when people elect someone, we must accept him," he wrote.
The former education minister also wrote those who had no direct role in drafting and approving the constitution should also be permitted to hold positions created by the new constitution.
The only groups that he thinks should be partially banned are those writing and approving the charter.
"They shouldn't be allowed to hold positions in independent organisations and the Senate unless the charter requires the two bodies be elected and linked in some ways to people," he wrote.
Mr Chaturon also wrote all members of the five bodies should not accept the unelected prime minister post. "This may not need to be written down in the charter. Their words are good enough," he said.
Amnuay Klangpa, a former Pheu Thai MP for Lop Buri, also said he disagreed with the ban.
"I'd rather not see them banned. They should be allowed to run for MPs or senators so long as they are elected by the people. It's not a case of perpetuating power if the people choose them. But it will be inappropriate if they are appointed.
"I urge members of NLA, NRC and CDC to run for MPs in the 250 constituents. Personally, I'd prefer to have 375 constituents and 125 party-list MPs. It doesn't matter how they are calculated," he said.
