Also: the actions for which JPM was recently fined concern primarily the years 2007 and 2008. JPM may have acted differently in the 1990s, but that's practically irrelevant to what happened ten years later -- especially given the extent to which the size, and the number of unsophisticated investors lured into Madoff's scheme (with JPM's help) increased geometrically.
Similarly, whether they reported him to British banking authorities is also of little relevance. U.S. laws concern JPM's obligations to report suspicious activities to the SEC and other domestic agencies -- not the Brits.