No, not really. Your quesion is an example of one of the more prominent, in my opionion, 'stereotypical' views of the Communist Party of Kampuchea's revolution in Cambodia.

There are numerous ways to go about this, but perhaps the most simple is to address some of the points in your question, which seem to lead into your actual question.

So, the CPK decided to empty the remaining towns and cities that were not under their control by April 17, 1975, less so as a deliberate form of genocide, but in order to 'sweep clean' the country in order to a) fully institute their regime with no enemies from the previous one, and b) to better serve the goals of their revolution. Some academics have offerred general anti-urban ideological sentiment to the mix here, which I'm not going to disagree with - certainly the bulk of the armed forces who entered Phnom Penh that day were primarily drawn from the rural peasant classes who had never set foot in the city. They had been told that it was the bastion of the bourgeoisie, that the people there had been trying to kill them.

But again, the emptying of the cities was a multi-reasoned policy. Aside from supposedly unearthing all these 'enemy-enclaves', they were also able to transport huge numbers of people to the areas of the countryside most important to the first part of their revolution. Producing a super great leap forward on the back of the strongest (almost only) part of the Cambodian economy - rice.

They meant to 'proletarianise' the whole of the society through this work, many of whom had already been under CPK control for years during the Cambodian Civil War. Here we have the distinction between the so called 'base/old people', and the 'urban/new people' from the forced people movements.

Now, the main parallel here is the Mao's Great Leap Forward. But before we get there, there is one part of your answer I want to dig down on as I think it will help:

Did the Khmer Rouge believe that all civilization was bad, or only post-industrial?

The Communist Party of Kampuchea were communist, they didn't think civilisation was bad - they had a marxist world-view which saw these economies and revolutions on a linear path toward communism - they were the vanguard of the Cambodian version of this. For instance, look to documents surviving from Party Centre meetings in July 1976 to see their 'plan', in action. Recorded in Kiernan, Chandler et al Pol Pot Plans the Future, we see the CPK call for 'socialism in all fields', and set out their plan from a basis of agricultural produce to provide the income needed by Democratic Kampuchea for autarchic economic growth. They simply didn't have many other resources in the country. The plan called for the doubling of rice production by the end of 1980, the income being used to purchase more agricultural machinery and other industrial equipment. The plan sets out how they socialism could build their light industry, then heavy... communications, transport and telecommunications, "in order to punctually provide for increasingly high living standards of the people".

This idea that the CPK wanted to take Cambodia "back in time"... is one that really isn't applicable. I believe it stems from the overuse of the term "year zero", which was a French Revolutionary term originally - and popularised in the Cambodian case by the publishing of Francois Ponchaud's influential book of the same title while the regime were still in power. The CPK never used the term.

Again, the key to their entire revolution is the Great Leap Forward, the CPK wished to have a total revolution in record time, they believed the Chinese hadn't gone far enough... They didn't wish to go back to a hunter gatherer society, they wished to produce the most pure communist revolution of the 20th century.

Phnom Penh did not remain empty... There were still around 50,000 people who remained in Phnom Penh or were sent there after the liberation in April '75.

Andrew Mertha, in his book "Brothers in Arms: Chinese Aid to the Khmer Rouge", states that there was a section of the city where the foreign embassies were set up, as well as the shops that these diplomats were able to visit. Various factories, warehouses, hospitals, motor pools and logistics stations were scattered around the city, but movement was strictly controlled and enforced. Particularly sensitive areas, such as the S-21 prison complex, were surrounded by a kind of ‘buffer zone’ so that the activities taking place there would not be noticed by outsiders.

So it was certainly not empty, and the various ministries that were set up would usually mean that top officials and their families may also be relocated to the capital. The airport remained functional and the city, to some degree, was morphed into something resembling a hub for the regime. Zone leaders and cadre could be summoned there, likewise foreign dignitaries who visited. Even some of the 'new people', those who actually did count themselves as technicians and similar, were actively picked out of the crowds leaving Phnom Penh - not for execution - but to work back in Phnom Penh and 'keep the lights on' as it were.