What auditors do
You are confusing the roles of the auditor and the financial due diligence team.
The auditor reports on whether the accounts show a "true and fair" view of what happened. They do not report on:
- whether what happened is likely to continue into the future; and
- whether what happened was actually a good business proposition (you can make the dumbest deals in the history of the world and still have a "clean" audit report).
Specifically: the allegation that Autonomy inflated its sales by reporting hardware transactions. Provided that the transactions occurred, even if at nil margin, they are arguably sales of the business and could be reported as such.
The firm doing the due diligence, however, should have picked this up and highlighted it to HP. Whether they did, and whether the right person in HP was reviewing their reports, will eventually be unearthed in the courts