The stand out comment from the article was how the owner said he wouldn’t have done it if he knew what he was getting into.
Being in the thick of things of course the trauma will fade but my limited experience empathizes with his pain. Half jokingly half seriously I would say retrofitting a commercial space in a building like that you would have to take your budget, then double it. At least probably he didn’t have to re-zone or change the usage of the space. Water, sewer, hydro etc. upgrades to satisfy current code requirements or change the usage can eat up the entire project budget without touching the building itself in some of these cases. That’s not work in the space or building ibut rather work out on, under or above the street you are required to pay for just to get the service upgrades to the building.