Class struggle entails shifting balances of power.
Many groups are interacting within each side.
Workers currently have little power, but the UAW action has so far seemed as one of the most momentous opportunities in recent memory.
Building power depends on seeking gains that may be expected to be both reached and to be held. Once a stronger position is reached, then the even stronger position becomes closer at hand.
You are suggesting throwing everything at a single opportunity within a hostile and untested climate.
It is wise to seek modest gains one at a time, trying to encourage everyone that better days are coming soon.
At the moment, even a substantial symbolic victory in one area would be quite significant in terms of building momentum to expand movements across the working class. When one group of workers rises, even by only a modest increment, we all gain power in the shared struggle, power we can use to climb higher.