If tofu and beans supply adequate nutrition but cost $1 more per week than meat, the study design would conclude you "must" eat meat.
Not everyone in the world makes 500k + stock options to tap at a keyboard a few hours a day.
I don't think a hypothetical $52/year increased food cost requires a half a million dollar salary. I don't make great money right now in my non-tech job, but beans and tofu are still on the menu.
A package of tofu costs $1.99, which is enough for a meal for 2. How much does meat cost you these days? This trope is so tired.
Buddy, I have as much contempt for the 500k + stock options keyboard jockies as the next person.
I am down with your "must". Its may be technically valid within the constraints of the paper - no supplementation, no higher cost etc, but it as a word has little place in the title of an academic publication.
My contempt is for the "people should just spend more money" crowd.
I may be wrong but the meat and dairy industry get a lot more state subsidies than their plant-based competitors.
Also, where in the world do beans cost more than meat?