Not sure I'd call ZDT an action film at all. It has a few moments in it, most notably the ending 20 minutes but even those are more about the tension than what action takes place.
I'd counter with the notion that people were more interested in Gangster Squad
for an action alternative if just movie options was the point of contention.
When a movie does this poorly it would be nice to have a clearer picture of just why people didn't show up. Arnold got positive mentions in Expendables so you'd think if just his core base showed up the movie would've done $15-20m. Could people involved in Inauguration activities have hindered things. Tack on the NFL conference games on Sunday as another possible thing that kept people away from that type film that Arnold does?
People still went to the theater obviously, if your name was Jessica it was a stellar weekend. I haven't read yet and it's usually reported at some point what the year-to-year comparison would be for a holiday weekend. If it's down overall that would lend credence to people being broadly distracted by other events and Arnold's base just got hit harder.