It sounds like they know certain assumptions regarding parameters that are not of interest are wrong. So why explicitly model those, if we don't care about their distribution? We (apparently) only care about an accurate estimate of W boson mass.
Is there a concrete reason we can't be naive and just bootstrap confidence intervals for example? Of course I defer to the physicists here – but I'm curious whether there's some simple high-level reason the usual tricks don't work.
See also: https://twitter.com/pietrovischia/status/1512174848558219270
This does not seems like bleeding edge, it seems like "Gaussian approximations for everything."
In fact, this is the reference for the technique they used: https://cds.cern.ch/record/183996/files/OUNP-88-05.pdf. (Although the criticism seems to be leveled at the way they estimate the correlations, not that linear estimator specifically?)