Yes, you can transmit messages via SMTP using TLS, but you don't need any special tools to read the email once it's reached its destination which is the point you seem to be missing. And before you scream PGP, almost nobody uses it.
But that's exactly the same as anything else; you move git commits that you store locally (either encrypted or not) over an connection that's encrypted in transit (whether SMTP/TLS, HTTP/TLS, or git/SSH) to a remote server that stores the repo/commits (either encrypted or not). None of this is different depending on whether the remote is a mail server or github (or whatever).
TLS secures your message till the endpoint which is a (plaintext) code repo. Why would you want a special tool to read plaintext code? Your argument makes no sense whatsoever.
I’m not sure what you’re getting at here but it sounds more like an irrational hatred of email than something genuinely technical to me.
Like a mail server?