Did you read the full article? I was expecting some evil screwing of their customers and putting themselves massively short on Madoff and them to have got off lightly but actually (based solely on this Bloomberg article) got the impression that the punishment was harsh.
From the TFA they were long but in the process of unwinding their position (albeit slightly faster than they helped their customers to do) and they filed the report of suspicions in London but not in the US (by oversight). The other problem seems to have been that the chinese wall between the speculators and the account managers was respected.
They were obligated to unwind their customers. They were obligated to report the crimes to UK authorities. I'm not impressed by the fact that there are aspects of this where they actually didn't break any laws, and it isn't a compelling defense for why they shouldn't be fined for the parts where they did.
I'm not saying that some punishment may have been appropriate but 1.7Bn plus damages on top seems plenty based on my understanding from the article rather than that they got off lightly as suggested by the post I was responding to.
The relevance of the report in the UK is that it suggests not reporting to the US was oversight rather than a decision to take commercial advantage of the knowledge rather than bring in the authorities (unless they were counting on the UK authorities being useless).
I think society would happily trade that for actual prison time for a bunch of execs who knew exactly what was going on.