Will Wong, on Logitech’s forums:

We’ve heard your concerns. We understand that some customers are frustrated with the recent security fix we put in place, as it closed access to private local API controls. While security continues to be a priority for us, we are working to provide a solution for those who still want access despite the inherent security risks involved. 

If you would like to participate in an XMPP beta program, which will allow access to local controls, see the below instructions. Over the coming weeks, we will qualify a regular firmware release that still allows XMPP control for those who need it. We expect to send out an update that will be available to all Harmony customers in January.

This is a good call. Pity it took a ruckus for them to fix this issue, but I’m just happy that I’ll get my HomeKit integration back.