Doesn't that 'echo' command go straight to the command history? It would reside in ~/.bash_history unencrypted until I type 2000 other commands.
Tangentially, if you precede a command with a space, then it won't show up in your shell history. (Double check to be sure, as this is likely a configurable option of your shell. e.g., 'histignorespace' in zsh.)
E.g., they’re not typing `echo` commands in the same way that they’re not typing `gpg "make-key"` (which is not a real command).