He's not making it up and there's no reason for that tone. Strings are more straightforward to isolate compared to vocals/horns/etc because they produce a near-perfect harmonic series in parallel lines in a spectrogram. The time/frequency tradeoff exists, but it's less of a problem for strings because of their slow attack.
You can look up HPSS and python libraries like Essentia and Librosa.
You can look up HPSS and python libraries like Essentia and Librosa.