This isn't true re: it being a sunk cost.
Real estate like that is actually (well, in the olden days) an appreciating long-term asset as well as a well-lobbied avenue for balance sheet games. Commercial real estate is subject to yearly depreciation, unlike your home. It can be somewhat arbitarily valued or devalued (see the games that Trump plays with real estate and taxes, sorry to introduce some politics), but generally real estate is tangible and appreciates long term.
Although if a company has a RECENTLY constructed office then it very much is a sunk cost, because the depreciation is on a 10 or 20 year schedule (don't remember exactly) and hasn't appreciated, and of course they haven't gotten the actual "house workers who make money for you" return. SO I agree with that. And of course all the companies don't want to see their already-depreciated by market appreciated values collapse under them. They want more sucker startups to but their appreciated properties once their business model ages.
Now, I guess we'll see how much the author's contention of a bubble/apocalypse plays out, but we'll know if office tower -> housing becomes a recurring thing. It wasn't with dilapidated malls, although it probably should have been.
As hinted at, the masters of office space are very well integrated with local politicians and the pork train. It's one of the pillars of local politics and local corruption. They'll try to find ways to get tax breaks or find a bigger sucker (like the local government!) to take on the burden or bail them out.