Contrary to what John thought, Sherlock did have some tact.
Some small tact.
Right as the shop was due to close, Sherlock entered the tidy shop, completely ignoring the wares themselves and carrying a small file. This was the sort of thing she would likely wish to confront in private, and frankly away from prying eyes.
Perhaps John had been right about not posting over the network, though. Tucking that away for next time, he handed the woman the file without preamble.