It has been discussed. How about something like:
Security solutions for HMIPv6 and FMIPv6 have been discussed, but the current design state for some of these solutions is tentative and experimental in nature. The Working Group expects that the protocol designs published as Experimental may not have security sufficient for production use, but that the requirements document will clearly articulate security requirements sufficient for production use. Specification of strong security solutions for these protocols sufficient for production use is a prerequisite for future standardization consideration.