The answer to this depends on information not present in the article, and is probably not possible to answer without an actual lawsuit. Are the manufacturers taking reasonable steps to avoid the problem? If so they're probably not responsible.

If there are internal emails at the company saying "well our testing shows it might kill people but we'll save 2 cents per brush if we accept weaker wire attachments" then sure. I doubt it's that clear cut.

No reasonable person would think that, no.