I think this tweet is wrong on multiple accounts
The main fault is the use of "natural". It does not make sense to qualify any process of urbanization as natural or unnatural. The fact that cities show a spatial segregation of wealth, rent and services is the product of a history of capital accumulation and land valorization in a class-based economic system. Calling any result of this natural does the bidding of those who have an interest in manipulating land value to their favor, it is a political process created by a certain set of agents in a set of concrete conditions.
There is also not much water in the European-US city duology. European cities have historically not had exclusively rich centers "naturally". Haussmann bulldozed the tens or hundreds of thousands of homes in the city center of Paris to rebuild it according to bourgeois aesthetic and class criteria, and many European city centers maintained worker's housing districts in their centers well into the 20th century. Milan itself saw a process of post-war industrial worker suburbanization and later gentrification from the 80s onwards. Generally speaking, gentrification and touristification is an ongoing process that is revalorizing the city centers right now, and one that isn't very old in the historical perspective of the city, even just the capitalist city.
The US city is the product of the process of racial segregation on top of the capitalist urban dynamics. More specifically, the product of some specific federal and municipal policy instruments: redlining, racially selective FHA mortgage access, the Interstate Highway Act subsidizing white suburban flight, exclusionary zoning, to name a few that aimed to produce a white propertied class. Even in US urbanism there is no settled urban model. Burgess' very well known 1925 concentric zone model of the Chicago School of Human Ecology introduced the concept of the Central Business District, but it was also immediately contested. The model of the poor inner city pattern itself is mostly concentrated historically in the second half of the 20th century and in the Rust and Sun Belt cities. This is changing still, and gentrification has also hit US cities like New York, San Francisco, Washington DC or Chicago with dramatic restructurings of their centers. The capitalist city is not spatially stable.
Calling this "social engineering" is bizarre and to me sounds more like a right libertarian talking point than anything else. It perpetuates the naturalization of the political-economic urban spatial segregation but in the other way (posing the US as being anti-natural, the wrong kind of segregated), and places the blame of spatial segregation on government policy rather than the historical push for that white propertied class to remain after the 13th amendment and after the Civil Rights Act.
The "wealthy city center" is not a stable category and it spatially shifts along with capital accumulation. Many US and European cities are seeing secondary CBDs, peripheral business parks, and Europe specifically is seeing the valuable center being stretched along transport corridors now. And this is just on Europe and the US. This all diversifies greatly when the rest of the world (the majority of cities) are taken into account with their own historical processes of spatial configuration. To name a good example, La Paz in Bolivia sees its poorer districts pushed to the periphery because the city is built on a valley and its peripheral urban growth is on the sides of its surrounding mountains; capital accumulated in the lower elevated center, and the working populations were pushed to the mountainsides. This is opposite to many European cities where higher elevation often (though not always) concentrates higher rents.