The protocol is quite easy to get into, it is well documented to the extent that it is easy to believe that it is in WireGuard's interest that more people develop software that supports the protocol.
Maybe the WireGuard homepage should make an official statement that anyone who implement the protocol and release a client is no longer welcome in the community to discuss the protocol or listen when other people discuss the protocol.
The WG author mentioned in the mailing list that he has reverse engineered Tunsafe and found security flaws. I would like to see that he presents these security shortcomings in order to legitimize his claim instead of keeping it secret. As he is a representative of a security company, it might be a good tactic to not hurt his reputation as it is practice in the security industry to share such information.