If you read the link, what's discouraged is using the non official client to connect to the Signal service, or using the "Signal" name on something that isn't p

If you read the link, what's discouraged is using the non official client to connect to the Signal service, or using the "Signal" name on something that isn't produced / run by OWS. There's nothing there about preventing anyone from running a signal-compatible service/network and shipping a fork of their own client to connect to it, which is my original point.