They know Pogacar will probably be stronger than both Roglic and Vingegaard regardless and the rest of the field will probably be weaker. They also know Van Aert will not stay long-term without giving him the opportunities that pretty much any other team would give the second-best rider in the world. Think it's less bravery and more something that's either pragmatism or indecisiveness, depending on how you look at it.
In that case van Aert would get much more dedicated riders and no way Roglič and Vingegaard (and Krujswik ...) would prepare as they did.
They are basically serious in their goals. That is they want to secure both yellow and green at TDF 2022. Now on how realistic such goals are by themself. And on why teams like UAE and Ineos would likely never approach it in this way. That can be discussed. Before and after the race when the results will be known.
But as for the idea they have given up before they started. I don't buy that. On the contrary.