It's a rather significant issue, if this is a proposal to ameliorate the risk.
On letters of credit, I've never met a letter of credit that can't be revoked. If you're meeting your solvency requirements with letters of credit and the company is in financial difficulty, doesn't that actually create a whipsaw effect, so that not only does the company have problems with its bank and balance sheet, but it now has an additional problem with its pension plan, because it didn't sponsor the pension plan with cash, it sponsored the pension plan with credit?
Doesn't that, in fact, accelerate your difficulties rather than decelerate them?