It sounds like your boss comes from a deposit servicing background. On that side of the ledger, account agreements commonly allow banks to change terms when they feel like it. Credit doesn't work that way. Consult with your bank's attorney and you'll learn that the terms of credit contracts can only be changed with the borrower's express agreement.
Customers who are not paying according to the terms of their agreements are subject to the remedies spelled out in their notes. If acceleration is one of those provisions, then feel free to pull the plug. You would then be free to negotiate alternate financing terms if you want to keep these customers.
Customers who are paying as agreed are "good customers." As long as they comply with the terms of their credit agreements (no matter how much you dislike those terms), you can only wait, watch, and be prepared to jump in the event of default.
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...gone fishing.