It was a loophole, a stupid one, but a legitimate one. However, as soon as the penalties came down for essentially being too smart for their own good (great idea, failed execution), they needed to be followed. Di Grassi wound up looking like Scott Goodyear at Indy.
The standard of driving in London was very poor from very experienced drivers who should've known better. Between desperation and a bad layout too many people were playing bumper cars. I agree with the complaint that Formula E need to stop having so many random post-race penalties for technical infringements the fans cannot understand. That costs legitimacy and needs to stop. But the driving standards penalties issued because some guys were just blatantly torpedoing their rivals were entirely correct. Once you allow things to go down the BTCC road, it is very hard to recover. That's a risk they need to avoid.
Audi aren't really any more jerks than anyone else, but ignoring the black flag just looked bad for them.
All of that said, I can think of some pretty poor driving at times in IndyCar this year, from equally experienced, big name drivers, and F1 continually sets low goals in driving standards and fails to achieve them. So, I don't think there's any need to single Formula E out as egregious in this respect. You give a bunch of egomaniacs carbon fibre law darts to play with, and they will try to put each others' eyes out. That's partly why we all tune in.