I'm not qualified or interested enough to investigate this but I can tell you that on Windows Trend Micro have blocked keybase as potential malware. It's reported on github and keybase have requested an exception but reading your post one starts to wonder why Trend Micro would get that idea.
I'm glad you showed me that but unfortunately I'm required to run it by my organisation. And even if I do disable it we have VPN software that requires some sort of AV before you're granted access.
