This email strongly suggests breach of confidentiality -
JPMorgan was given access to WaMu's books in good faith to make a buyout offer that was eventually rebuffed. "(Dimon) thinks the potential losses are higher than TPG is estimating" is a qualified response as a result of the due diligence produced from these negotiations, and the statement is disclosure of material information to a competing firm (that is, between WMI and Grupo Santander).
Dimon's candor indicates JPMorgan was not in a good faith position to purchase WaMu for its real value (mark-to-market) because JPMC's own condition was tenuous at best - so the potential exposure to losses and the regulatory pressure to maintain capital requirements could be too much to bear (remember this was 2008, after all).
It appears Project West was conceived to acquire WaMu for next to no consideration through regulator sale, marking down asset portfolios wholesale, and reaping the bounty thereafter.
From today's Barclays presentation by Jamie Dimon:
Strong organic growth consistently year after year and lift from WaMu acquisition
WaMu was crippled by NSS - to the extent that JPMC-sponsored MMs participated in this may yet be disclosed by the Examiner.
As for me, I'm with GO4 to ride out the MOASS lol
A historical chart for WM (annotations are not mine)
List of writedowns and loss reserves by major financial firms prior to WaMu's seizure: