Dave Grohl drags Taylor Swift on stage in London
It would not surprise me at all if the TSwift band was faking it live. Most of her songs now are just sequencers and midi, written by the producer...there isn't much for real musicians to do. At any rate her show is probably full of backing tracks to do the stuff that the real players cannot do. It's super common. I kind of hate it but nowadays people expect the show to sound like the record. If you layered up 3 drum machines, a real drummer/percussionist, synth bass, 15-20 synth tracks and 35-40 vocal tracks it is basically impossible to replicate it live.
That's why I prefer rock and roll(which is now mostly fake as well as using the same techniques).
Anyway Grohl should keep his mouth shut unless he knows something for sure.