Porcelain runs on your Mac and keeps to itself. It has no analytics, no telemetry, and no account to sign into.
Your code never leaves your machine.
Porcelain reaches the internet for one reason: to see whether a newer version is available. It asks the release server what the latest version is. That request carries no information about you or your code.
Porcelain is open source, so you can check any of this for yourself.
Read the source