I think the author misses the point on what is being disrupted. It sounds like he thinks a law firm that adopts a better version of office is being a "disruptive." He says that if a business is constantly open to change, then what's the point of disruption? He confuses the role of adaptability and who the disruptor is displacing.

Think about the first word processor compared to a typewriter. A company's choice/ability to adopt the word processor didn't make them a disruptive company. However, the word processor creator entirely disrupted the typewriter company.

In the author's article, he references Office 365. Incorporating new features of 365 as they role out does not make the 365 customer more or less disruptive. What's disruptive is that 365 is attacking dropbox / google docs / other service providers.

In fact, when the author asks is the term "disruption" relevent if businesses become adaptable is kinda silly. Adaptable businesses open up opportunities for more disruption. If a business is willing to take on new ways of doing things then they are more likely to become customers of a new disruptive product or service, whereas old non adaptable businesses would limit the new product's potential client base / make it harder to find first adopters.