First, I think that the right choice is to pick the right protein for the job, and not choose wheat and soy because of price. Mung beans, for example, are expensive because people aren't growing them. If quantity demanded grows, so will supply and supply chains, which will lower the price. It is possible that mung beans (as an example) are marginally more expensive to grow for some reason other than scale, but I would be surprised.
Second, I think they are getting cause and effect mixed up. They are saying to go downmarket because it will be cheaper, but it is much harder to beat Tyson at its own game with chicken nuggets than it is to provide a product at a higher perceived quality, then use profits to provide scale to go downmarket.
Plant-based versions already suffer from a perception of lower quality - it makes sense to compete on taste before cost because failing at both will never scale.