Do you got any evidence that they are changing anything? Talk is cheap, any links to an article where they actually changed something and not just them talking about changing things?
Edit: The main reason to be wary of "fair" brands is that they put extremely huge markups and motivate that by paying a tiny bit more for their parts, making them really profitable. You'd need to show people that it is better to pay for a fairphone and that they actually deliver on their promises, over paying for a cheap phone and donating the difference to a good cause.