>>715746063
If you chose to destroy the Mechhive Cerebrex Core, all (vanilla) hostile mechanoids from then on turn up deactivated, whether they come from events or even stuff like ancient dangers. Colony Mechanoids that go feral because their controlling Mechinator dying also becomes deactivated. For that colony run, you pretty much permanently disable Mechanoid raid and cluster drops, and it also disables the ability of your Mechinators to summon Mechanoid commanders (bosses). All of your colony Mechanoids still function and you can still gestate more though, because they're linked with your colony (and your Mechinator), not the Mechanoid Hive.
As for modded Mechanoids, who knows. For the ones that come with HAR races (like Miho and Milira), they're probably immune to that because they're not Mechhive Mechanoids, but faction owned, so to speak. Though Alpha Mech ones should stop, unless the dev wants to pull some 'acktually Alpha mechs are capable of independent movement' kind of thing (I haven't checked to see if their mechs also get deactivated).
Spoiler for if you didn't destroy the Mechhive Cerebrex Core and took it instead:
You get a Utility Slot equipment that when equipped to a Mechinator gives them +15 Mech Bandwidth and +12 Mech Workspeed Offset. When the pawn equipped with the Cerebrex Core is drafted, they gain three abilities: the ability to summon 2-3 Mechanoid Drop Pods for your own use (free Drop Pods, pretty much), the ability to summon a hostile Mechanoid Raid at the target location, and the ability to deactivate a Mechanoid within 30 tiles (I think it only deactivates one at a time). All of these abilities have a cooldown of like 1-2 minutes or something like that.