Mechs aren't objects, but they're constructs with the technological subtype. Construct is a creature type. They are never explicity called creatures, though, and the example blocks are written with the frame name (Gargantuan blinkstriker, etc.), so it's vaguely ambiguous.
A reading of them implicitly not being creatures and explicitly not being objects would mean they are untargetable by a vast number of abilities (including plain damage spells like explosive blast or ones that have effect on tech constructs but target creatures or objects).
My personal reading is they are creatures.
They don't have a Will save in the example blocks, but they have a 'base save bonus'. Nothing explicitly says they do not have a Will save, only that components may increase fort and ref. Also, even objects have will saves, so them not having one at all is weird.
Override can be used on 'creatures with the technological subtype'. As can ghost in the machine. Unless mechs are ruled explicitly not creatures (by GM or Paizo), then GitM opens up questions about what 'dictating its actions' entails. I'd probably just let them reuse it for the daze to start.
A small number of similar weird interactions exist if they're creatures, but far less than I expected (eg staggered is rough on 2+ operator mechs, I gave them polymorph immunity for baleful 3+ and poly 6, and I added a will save increase method). And none of it seemed as bad as making people cry when they can't use any effect that isn't at a 'target' or 'enemy'.
The 2+ mecha operators is also confusing...
I used to run a mystic who used demoralize in combat. Could she do that to a mecha? Does it work on one or more of the operators or on the mecha itself? She used mind thrust as well. Does that do damage to the operator or to the mecha?
I honestly dunno. I'd really like to include mecha in my next AP, but it would be nice to have clarification to the rules, so I'm not adjudicating them on the fly and my players can know what they should and should not do when they are fighting against or in mechas.