Trying to complete production orders while running inventory close in AX 2009

We recently upgraded from AX 3.0 to AX 2009.

Now we find that we cannot complete production orders while the inventory close is running.  This is by design in AX 2009.  In the class ProdUpdHistoricalCost.Validate() method it is checking for a currenlty running inventory close and returning false if there is one.

The error message is "A not properly finished or canceled inventory closing exists".

Is there a reason for this?  In a test system I commented out the check in the Validate() method and posted production while the close was running.  Would this be an unwise thing to do in our production system?

In the Inventory model groups, we are not using AX 2009 Standard Cost.  We are using FIFO with Fixed receipt price checked ON - this was called standard cost in AX 3.0.

Thanks for any advice.