I wonder if I would have said anything if I had been a witness
If I am ever a wittness to something like that (or more likely, accompanying MIL when she sets off on insulting everybody from Southern Italy/Another Country and the surrounding gen pub naturally enugh looks it it would like to lynch her) having thought about it...I am going to start singing We All Live in a Yellow Submarine or Immagine (or something like that, but in Italian) depending on which one I think I can remember the words to. Really Loudly. And Clapping Along.
Best case scenario everybody will join in, lose the feeling of impotence to do anything cos intervention carries the risk of inflaming the situation, unite them in a postive way (so they feel less like clumping her, and can show solidarity with the people at the sharp end of her tirade) drown her out and with any luck she'll join in and forget she hates everybody today, or just mutter in a mammoth sulk.
Worst case scenario I'll feel like an utter twat, but at least should draw attention away from the person being vile, and it make it less easy for people to hear exactly how offensive they are being.
We already use the singing thing at home to break the rising tension, unite and drown out the vitriol (her neighbours just love us, its either ranting and raving or impromptu sing songs) when she has one specific person as her target, and it works. So perhaps it will work in a more public setting too.
I'm just immagining that bus bursting into song and taking the aural space back forcibly, in a very peaceful fashion.
It's a nice idea in the theoretical, just hope I never have to put my (really horrible) singing voice to the test.