This summary is not the rule. The rule text controls.
If you work as a lawyer under someone else's supervision, you still have to follow the same ethics rules as any other lawyer. You can't excuse bad conduct by saying your boss told you to do it. Every lawyer is personally responsible for following the rules, no matter their position in a firm or organization.
That said, the rule gives some protection to junior lawyers. If there's a genuine gray area about what the right ethical choice is, and your supervisor gives you a reasonable answer on how to handle it, you can rely on that guidance. You won't get in trouble for following your supervisor's reasonable call on a tough judgment question.
The line here is between real judgment calls and clear violations. If the ethical answer is obvious and your supervisor tells you to do something wrong anyway, you can't hide behind their instructions. But if reasonable lawyers could disagree about the right approach, and your supervisor picks a reasonable option, you're covered for following their lead.