This isn't a fundamental issue with composites. Although they do require more stringent process control than traditional metal structures, with good procedures and QC they are extremely strong (and have significant advantages over metal structures--we've just been working with metal for so long that we know a lot about its issues).

The main question is whether or not Boeing fundamentally has good procedures and QC--if those have been compromised, they can't really be trusted to make mostly-metal airplanes, either.