Create a BOM Header UDF to achieve the same functionality. Stupid yes, but it might work. What if you change the item to discontinued instead of inactive. This might allow you to SO the item and still change the BOM to inactive?
The entire SO|IM|BOM functionality REALLY NEEDS to be rethought! Client explodes their BOM on a SO as a shop floor order. When the BOM is marked as a Kit, they can't do a cost roll up to IM. Has to be a standard BOM for cost roll ups. Then there is the problem of using misc codes for labor and overhead. You can use in standard BOM but not a KIT (or is it vice versa). As it stands now, it is an 85% complete solution at best. To get it any closer, you have to jury rig the process. Totally F'ing stupid................ TLTF.