I was trying to implement gen_icmp earlier via socket and encountered that problem. So instead I created PR to the core that fixed checks for {type, proto} pairs and now it is possible to create such socket. I think that he meant that they will not implement ICMP helper function directly in OTP, but manual implementation via socket should be possible (on supporting OSes, as traditionally ICMP sockets needed to be created as raw sockets which can be created only by superuser).
