Whether the legality of the claim allows it, it is unethical to use the words all natural or green when advertising a product. The age of green washing is calling bullshit all over the place and it's finally time to move into the phase of transparency. It's about knowing the science to make a credible claim.
It says nothing to talk about being "green." When advertising a product people need to talk about the specific things that make it sustainable and express the sustainable value of the product. Promote blue because blue means sustainability. They need to define why the product is good from the green perspective and bring it into real life situations so that consumers can understand its benefits.
Employees can really make a change at the grassroots level. If they speak to their customers about the right products to use then they can become a successful resource of marketing and can become really involved in bettering the company and customer's sustainability.
A big theme is "make a change but shut up about it". However, it is important to use communication to accelerate the positive change. Once the company has invested enough and there is no point of return then it is very important to communicate and get the message out. You need to justify the time and energy that is put into making a company sustainable and still need to be gaining in business terms. If the company is investing capital, then they should be talking about it.