How was that understanding reached? The $25m was written off as bad debt and hence deductible. Debt you still may collect can't be written off. One can't have it both ways. The IRS defines bad debt in the following way: "You have a bad debt if you cannot collect money owed to you. A bad debt is either a business bad debt or a nonbusiness bad debt."

Investopedia
Definition of 'Bad Debt'

A debt that is not collectible and therefore worthless to the creditor. This occurs after all attempts are made to collect on the debt. Bad debt is usually a product of the debtor going into bankruptcy or where the additional cost of pursuing the debt is more than the amount the creditor could collect. This debt, once considered to be bad, will be written off by the company as an expense.