Apple, like Microsoft, Google, and others has a real web of dependencies for all its software. Even if he did back up all his important data, unless it was in an open format with open metadata it probably still requires an Apple program to open, which will require his Apple ID to be working. And every one of these big monopolists makes it really hard to fully export your data and metadata in a useful, unencumbered format because keeping people locked into their ecosystem is part of their business plan.

We're all doing the best we can to live in unregulatedcapitalismland while staying sane, keeping our data backed up, eating healthily, getting enough sleep, getting exercise, spending enough time with friends and family, and so on. Things eventually slip.