alt Hacker NewsIn this context it would presumably mean not casually deleting your customers' data.
When people say a company is unserious they almost always mean that they're not thinking about, and taking seriously, the work that their customers do. This seems like a classic example of that.
Unprofessional or irresponsible are more applicable.
Some define a standard others set it. This came up when my employer was applying for business continuity insurance