You're just guessing, right? Because this really doesn't fit that well.
>war is over
>decepticon stragglers
props for trying to make sense of it, though.

 

The US Congress rescinded the Autobot Alliance Treaty in DOTM. Among the stipulations of the treaty was not messing around with Cybertronian technology and artifacts.

The war was over as there were only a dozen or so Decepticons around as per AOE dialogue with the majority gone due to the ships sucked with Cybertron.

However in TLK a new wave of Autobots and Decepticons are arriving on Earth at an alarming rate leading to the formation of the TRF.

 

riiight, why were they arriving again? something something talisman unicron
I can't remember at all now.

 

Kinda like homing instinct me due to Cybertron being brought by Quintessa and Unicron being Earth.