You nailed it! The fact is, there was NOT a "red swingline stapler" model until AFTER this movie! Now it is the stuff of folklore.
And, note that this movie was shot in Austin and Dallas, TX. I am very familiar with the office park where the office scenes were shot, I used to live just a couple miles away. I forget what restaurant they used for filming, and I have never been able to figure out which apartments.
I "think" that Mike Judge must be from Texas. And, that also explains why the printer scene uses the Scarface/Ghetto Boys music (Tx based artist). Note that Scarface plays UpGreyed in Idiocracy too.
en.wikipedia.org
Swingline introduced a red stapler to its product line after the Milton character used one painted that color in the film.