It may be the ID alone would be sufficient to establish contact. If this works the way FaceTime screen sharing used to would have be on FaceTime with him and manually grant him access. As I said I thought FaceTime screen sharing had been deprecated in Mojave and later versions of MacOS, but I may be misinformed. 🤷â€â™‚ï¸
I was recently working with Apple Tech Support and the Apple ID (email address) that is used for iCloud sign in and no password was enough to establish screen sharing in Mojave.
