This is just one aspect of a much larger issue: deprioritization of bibcodes. The bibcode will no longer play a central role and this service needs to reflect this. This particular issue mostly serves as a reminder of how quickly bibcodes are thrown into the mix when finding a solution.
When a fielded XML reference is submitted, unless a DOI was specified, almost the very first approach of finding a solution (when year and pub are in the submitted metadata dictionary) incorporates the construction of bibcodes.