I think you're right, that would be the best way of presenting this argument to management. To do so, however, the company would need to calculate its Total Cost of Downtime (which probably isn't very complex for many companies) which is its own subject entirely IMO.
If expanding to another region costs more than just taking the outage, then it's categorically not a good option. If management still says no in the face of numbers that suggest yes, then that tells you that you're missing a hidden objection, and how you proceed will depend on a lot of factors specific to your situation.