How did such an idea come about? PM mocks Suthep's call for him to carry on as PM

Suthep is the former leader of the now-defunct People’s Democratic Reform Committee that staged mass rallies in Bangkok against the Yingluck Shinawatra government prior to the military intervening to take power in May 2014.
Prayut replied briefly in a high pitched voice: “How did such an idea come about?”
Speculation has swirled after Suthep stepped out in firm support of the former Army chief continuing to lead the country after the election.
However, the PM made no further comment. In fact, it was the fourth day since he warned that he would not be speaking to the media for a short period.
The election is coming into sight, as charter drafters submit organic laws to the National Legislative Assembly for enactment, and some concerned individuals have made moves. 
Some former senior members of the PDRC have expressed their wish to return to the Democrat Party, which they left prior to joining mass street demonstrations against the Yingluck administration and its contentious amnesty proposal. 
Debate about the new government and who will lead the country after the election has surged, especially within the Democrats.
Prayut attended at a Farmers’ Day ceremony and said that the government was sticking to its roadmap, while also asking for cooperation from all sides so that the country can move forward.
He said although his government did not come from an election, it had managed to restore peace to some extent.
If people wished to see the country move forward with peace, they should cooperate with one another, he said.