Both of these positions can be true, or may be spin. Without knowing the basis of all the adjustments (not just those at one station) can we be sure which is which. That said, it's not an insignificant issue if a trend is only apparent in the data after adjustments are made because those adjustments are often just educated guesses which introduces a larger margin for error and the possibility that subtle biases affect which way and how far that educated guess goes.
In their explanation of the adjustments to Wellington they used the differential between the Airport and Kelburn to calculate the differential between Thorndon and Kelburn because they are at the same elevation. But is it really likely that elevation is the *only* factor causing the temperature difference between Kelburn and the Airport? The bits of Kelburn above 125 meters look like relatively leafy hillside suburb of Wellington, while the Airport is a pretty vast expanse of concrete. Is it really a good proxy for the Thorndon waterfront of the 1930's just on the basis that they're at the same elevation? What if we decided to make a cooling adjustment over time to account for the increasing heat-island effects of increasing urbanization?