Is this legal?

Saw this while stuck in traffic on the M6 this morning.

Clearly someone has an axe to grind with the two people concerned but this coach was covered in these photos and some short explanation of what had allegedly taken place.

They may well be in the right but, is this type of action legal?

BTW. I was stationary with my handbrake on whilst taking this on my iPhone.

PS. Thanks to all for the nice comments you made on the safe return of my iPad yesterday. And not one of you mentioned the fact I have a lorry as my wallpaper. Well done y'all.