Right. That's a forgery - a lie. No blockchain could prevent that type of lie. What a blockchain could enable is honest transparency.
An attempt to pass off a lie as truth would be much more damaging to a company's reputation than would be just not addressing an issue. By addressing the issue and introducing a channel for transparency, the company is demonstrating that they are willing to put their reputation on the line.
I would agree that as a regulatory measure, this would not solve any problem. But as a self-imposed measure, it builds consumer trust.
For example, international conglomerate using exclusively slave labor inputs "these bananas are small farmers fair trade bananas" into blockchain.
That's it. That is the "transparency".