I think we need to ask why our government is arguing against raising punitive tariffs on Chinese steel
We are a net importer of steel. Putting tariffs on Chinese steel would therefore increase prices for consumers. Those countries in favour of these tariffs are, in the main, net exporters of steel and therefore would not be affected in the same way.
It's telling that nationalisation is not ok for a major and strategic industry like steel but is vital for RBS and Lloyds
They were temporarily nationalised under a Labour government, of course, and neither was fully nationalised. If they had been allowed to fail the damage to the economy would have been huge which would have hurt all of us. Whether or not steel making is major and strategic is an interesting question - personally I don't think it is either. If it fails it will be damaging, particularly to those who lose their jobs as a result, but nowhere near as damaging as failure of the banks would have been.
If we want to save Tata the sensible move would be to exempt them from green levies as the government promised a while ago. They currently pay far more for their energy than steel plants in France and Germany as a result of these levies.
We need an economist in charge
We don't. The record of economists that have tried to run economies is poor. The job is more about politics than economics.