NiteStar, Exodus is NOT canon to G1. Exodus has NOTHING to do with G1. It did NOT tell the story of the war before they came to Earth in G1, it instead told the story of the war before they came to Earth in PRIME. And that story is far from complete. Exodus is only the first chapter of the pre-Earth war story, since Exiles picks up after it and continues the war with it set on the lost Cybertronian colony worlds like Velocitron and Gigantion. and then there's still millions and millions of years of war stories to be told before the event of the Prime cartoon even begin!
Exodus is as much connected to G1 as the Movies, Unicron Trilogy, and Animated are.
The G1 cartoon is not the end all, be all, Word of God version of the Transformers franchise. You claim that the Combaticons' history in Exodus defies their origin in the G1 cartoon, yet their G1 cartoon origin itself defies their origin in the G1 Marvel Comics, in which they were created on Earth by
Megatron and implied to have been born from the stolen power of the Creation Matrix just as the Stunticons were. And even before that, they were seen in a Marvel UK comic story in which they were seen in a Matrix-induced vision inside Buster Witwicky's mind.
Also, if you've got a problem with different continuities, well, tough. There's over 75,890,007 realities, and we're stuck with them.