Official support and not interfering with it being put up are nearly the same thing. It's not like throwing up a statue is some complex operation only governments can carry out.
“Officials knew in advance and helped or actively decided not to interfere” is NOT nearly the same thing as “Banksy’s team used social engineering to blend in and go unquestioned”.
The claim was that they had government assistance doing the project. IMO that’s just a conspiracy theory to explain what “bunch of construction workers with flatbed truck, traffic cones, and high viz vests” sufficiently explains.
