It probably took place somewhere near the Orange Line on the T.

No CCW in Massachusetts, but you can carry pepper spray (albeit, only after getting your FID card from the police). A big can of Fox or Inferno OC spray would have been much more useful in that scenario.
Of course, not getting out of the car in the first place would be better.

In this day and age, it is almost guaranteed that any altercation will be filmed by somebody. This is why it is imperative to follow the laws, avoid confrontations, and adhere to a force continuum. I tell my students that during a fight, they should pretend that they're being watched by a LEO and 12 jury members. In the video above, even though the guy was attacked by a group of thugs, he would be legally in the wrong since he got out of the car and challenged them.