Ok. I'll get it and post it for you.
It's not from a specific distro, though it was compiled on Slackware-11.0, though I doubt that specific version matters.
It is a completely standard rsync-3.0.3 built from source.
The only things you need to do to build it yourself if you don't want to trust a binary from some random person on the net:
1. Build statically. Your libraries are not going to be around on the target ESX box.
2. Build without TLS support. The mgmt kernel doesn't do TLS, so your binary cannot either.
3. Optional: strip the binary when done.
To use this:
1. All of this is unsupported. Take responsibility for your own actions.
2. Enable unsupported sshd to your ESXi system.
3. Place this 'rsync-static-stripped' binary into /bin or somewhere else in your path on your ESXi system.
4. You will probably want to rename this binary to just "rsync", so that you don't need to specify it on the commandline.
Note that you should probably not try to rsync any files that are currently in use.
There is no warranty and no guarantees of any kind.