I think they might be able to move a little bit. Not as much as the old-school suspended coasters, but I think those linkages are designed to allow them to swing rather than just offering some damping. Notice how in the top picture the last rows are banked out more than the previous rows. It looks to me as if the angle between the wheel assembly and the seat-support is different on those back rows.
The two dampers would resist this motion, implying they're expecting a fair amount of movement. If they were designed not to swing at all, they'd just use the natural damping in the metal and save themselves the hassle of having extra linkages and stuff.