The reason all your background information is irrelevant, is that it's not up to the employer what happens; it's up to the workers comp carrier. All the employer needs to do is report the accident; the rest is up to the carrier.
If you're thinking in terms of lawsuits, be aware that workers comp is no-fault. Your brother can't sue the employer, and the employer is on the hook for his medical bills and lost wages. Whether he was or was not trained properly does not come into it.