Trump does not have a unified national intent behind him. I don't agree with him or his policies, in this or any other regard but trying to think dispassionately, I think appointing Bolton to signal strength of will demands having somebody more flexible to negotiate the real outcome.
For example, Trump is probably going to lose the trade war over Iran. They need Boeing spares but if he continues to blackball Iranian trade the future air fleet will be Airbus with loans from Germany and France.
Trump is going to lose a trade war in China because China holds far more US debt than Americans hold Chinese debt and China has far more market reach into emerging markets in Africa since the decision to decouple trade and local politics was made clear: you can trade with China and continue to repress your own people or trade with America and have to clean up your act.