Citation needed.
If some people really do use that term, I strongly disagree with that usage in that context. And also with the reasoning behind it.
Vegans do not care about humans. They care about animals. A porn movie where they wear leather would not be vegan.
While you will find people that are exploited in porn, you will find such people in every business and industry. Porn is not an exception. And game development is not an exception either.
Also, you compare movies with games. Use it for hentai, if you must.