Inventory to_state = NONE

According to the docs, inventory adjustments can go from NONE to IN_STOCK, but no state can transition to NONE.

The NONE state is not a true inventory state. NONE is a from_state placeholder to represent the fact that a given CatalogItemVariation was introduced as new inventory. Inventory quantities can be transitioned from the NONE state, but cannot be transitioned to the NONE state.

However I’m looking at my real POS data and discovering multiple instances of inventory adjustments. I notice that these inventory adjustments seem to be coming from external APIs:
"source":{"product":"EXTERNAL_API", ..., "name": "WooCommerce" }"

  1. Why is this behavior allowed?
  2. Are there implications/bugs arising from this?