Deception is leading someone to believe something that isn't true.
If a deliberate delay is added to a UI to make it clear to the user that actual work is being done, this is not deception. You are leading the user to believe something that actually is true. The natural instantaneous UI is the deceptive one for a user who is led to believe that no actual work happened.
A fake progress bar that shows steady progress when the actual work is stuttering is not benevolent, unless you can be sure the operation will finish in a fixed amount of time approximately at the end of the progress bar. This kind of deception is irritating and not benevolent.
A fake progress bar like the way change.org petitions make it look like people are voting up the petition right now? That is deception, and regardless of the merits of the particular petition I don't think it's benevolent.