The idea is that in this case everybody profits. Universal gain ≠ personal gain, even if the campaigners are included.
In the case of Vince, everybody profits because of the sustainability, BUT he has another very clear personal economic gain and that makes his intentions questionable. It would be more easily accepted if there wasn’t this clear conflict of interests.
Oh FFS you’re really going out of your way to misunderstand the issue here. Nobody is claiming that the meat industry is good. People are just voicing concerns because a rich guy is doing what a rich guy usually does: defending his own interests above the common good. It might go in the same direction for a while, sure.