It should be discussed so kudos to you and your group Lars. It falls in the same category with Sarvangasana. And there are many teaching that pose flat on the floor such that the cervical spine is sacrificed or the risk thereto is magnified.
My belief is that many poses should only be taught to students who are assessed. A (healthy) student who does not clearly display the proper actions in their body in Adho Mukha Svanasana should absolutely not be taken up into Sirsasana. A student who has weakness in any of the four muscles comprising the rotator cuff; supraspinatus, infraspinatus, teres minor, subscapularis should not be taken up into Pincha Mayurasana (or chaturanga for that matter).
Unfortunately we (as yoga teachers) have not fully embraced two concepts. One, making safety a prime directive and two, continuing our education in such a way as to be able to execute number one.
I have and will continue to teach Halasna on the same propping that I teach Sarvangasana and ONLY to and for those students who’s body and body actions warrant it. When in doubt, modify, When in further doubt, substitute.