I do agree with your preference for the way this could have been handled. BUT, it is NOT too late to turn this around.
Yes, Trump could and should have immediately cited Judge Curiel's La Raza membership in the San Diego La Raza Lawyers Association as too inappropriate to be involved in his case based on a presumed prejudice. Based on that he could have asked why he's even a Federal Judge;
Trump could have also tied Curiel's loyalty to La Raza's agenda and goal to annex USA as part of Mexico. (THAT is where the "nationality" component of Trump's charge merits consideration.)
What Trump *did* do -- whether by design or not -- was scrutinize the questionable bonafides, credentials, and loyalties of federal judge, Gonzalo Curiel.
Why was a La Raza/"The Race" sympathizer with obvious loyalties TO Mexico of ALL people appointed to rule on Trump's case?
>>Why was a La Raza/”The Race” sympathizer with obvious loyalties TO Mexico of ALL people appointed to rule on Trump’s case? <<
That’s a good question. I’m at work now and can’t do any in-depth research, but I recall that the first judge on the case retired and he took over.
His lawyers at O’Melneny & Myers should have asked for his recusal off the top... not after an unfavorable ruling occurred.