Should any of us be upset over this? They made an annoyingly proprietary protocol that would be much more useful if it was open.

When comparing Sigfox to LoRa, they are not even that bad in terms of openness: The Sigfox protocol specifications are public: https://build.sigfox.com/sigfox-device-radio-specifications This is in contrast to LoRa, which remains a closed protocol (I am not talking about LoRaWAN, that part of the spec is open, but LoRa, i.e. the physical layer stuff). So there really is a tradeoff here: If you want an open wireless protocol compatible with many standard RF transceivers, but a proprietary backend and device library, go for Sigfox. If you want a closed, proprietary wireless protocol that only works with Semtech chips, but an open backend, go for LoRa/LoRaWAN.

Image that you can implement LoRa using GNUradio but you will exposing yourself to litigation. That's very problematic IMHO

Since several projects have done that one might ask them if they have considered this. For all we know, they may have discussed this with Semtech, in which case the status may be knowable.