The trouble, say Githongo and some of the businesses affected, is the haphazard nature of the demolitions, which they say come with little or no warning.
There have been chaotic scenes in busy areas.
On Thursday evening street children scurried through the rubble next to a traffic circle while workers attempted to bring order to what resembled a bomb blast site. Steel rebar and metal sheeting jutted into the air through piles of debris.
A man whose shop was torn down one recent morning argued business owners should be given notice when the government declared existing permits invalid.
"You don't just turn up with a bloody bulldozer," he said. "On what legal basis is this happening?"
In a statement, the Law Society of Kenya said: "Our environment and planning laws have evolved over time and in some instances, developments have predated the law. The state should ensure that the application of the current law does not result in unlawful deprivation of private property."
It is unclear how many buildings are at risk of being demolished.
The National Construction Agency said in a statement in March that nationwide 2,028 buildings, some of them on riverbanks, had been classified as unsafe.
Kenyan media this month said there was a list of 4,000 unsafe buildings in Nairobi earmarked for demolition by a committee appointed by the president. Dena, his spokeswoman, said she could not speak about specifics.
A wall of a 12-acre temple complex built close to the river by the Visa Oshwal Community of Kenya was knocked down last weekend. "We got all the necessary approvals that were needed at the time," said Jinit Shah, vice chairman of the religious group.
"Investors out there might be running scared now that the approvals granted by government bodies within Kenya are not now valid."
Nearby, the Ukay shopping centre - which contained a supermarket, restaurants, pharmacies and other shops - was simultaneously felled.
A week earlier, the centre's owners had been invited before the national assembly's committee on environment and natural resources to present their building permits amid the committee's inquiry into encroachment onto riparian land across Kenya.
The lawmakers unanimously assured them that their documents were in order, so it was a shock when cranes arrived just after 5 a.m. and began the demolition, said someone involved who spoke on condition of anonymity.
"The government has torn down a building which the same government had given us permits to continue operating," he said.
