Well.. All the SWAT/EFT guys know is that they got a call saying "Man With A Gun...", and they responded accordingly. You might argue they didn't need to throw the guy against a wall. But, I'm sure they also had the adrenaline pumping and their procedures involve removing the "suspect" from the area where the weapon might be
Case of mistaken identity, violating Firearms Rule #1: "Never Frighten The Horses" (i.e. 'anyone who might not understand'). Even for non-owners - While it may be perfectly legal to tote around a replica where you live. If you tuck it into your pocket or waistband, walk into a public place, and someone sees it... All the cops know is "Man With A Gun", and they're *going* to behave accordingly. Generally not a wise idea to be the poor schmo who fits the description.
In this case, it's really only funny because the "weapon" was made of Legos.