What it was exactly is not yet known but something went wrong, horribly wrong. The coordinates were exactly right, solar wind, drifting planetoids, the increasing dark flow, negative matter storms, every possibility had been accounted for. Even to the naked senses everything seemed to be correct, yet it was all wrong. Doubly so because the launch was aborted after all necessary calculations had been made.
Perhaps someone else did some piloting in the brief second he had left to check the oil levels of the engine? Perhaps there was some glitch in the system that rendered "abort" as "go to the exact opposite place of where the aborted coordinates were. Perhaps he had simply misinterpreted the instructions, expecting this new ship to work just like the old one, as Terrasaur suggested. His fellow Predacons believed the latter to be the most likely explanation but Scorponok insisted that he had done no wrong.
Regardless, this was not Earth. It looked deceptively like the planet where their ancestors did battle but Tarantulas's testing suggested this would only be 2004CE, if that were true and nothing matches up with the historical record, or indeed first-hand accounts-Rampage had been on Earth at that time and finds nothing familiar.
Ironically, one of the goals of this mission was to eliminate the hominid genus but if this planet was the only location with a human population it would accomplish little. Here humans are slightly more distinguished than common farm animals, forced to labor their masters refuse to do themselves or talking pets that make for a good source of protein in a pinch. Monsters rule this world, and their rule makes the Maximal oppression of the Predacons seem benign, the humans see the Predacons as liberators but the monsters see the cybertronian life as a living blasphemy against their deity.
Moo, they call him, a tyrant's tyrant. His rule knows no bounds, he even enacts laws for how many times a monster is allowed to breath in-between bites of human flesh, exactly what sound they are to make when lapping up water, the proper way to react to injury...Moo is likely on his trone drawing up new laws pertaining to the predacon presence.
Megatron is primarily concerned with gathering enough energon to make it back home with no stops, not trusting the spacecraft's computer to do that correctly and knowning the more courses to set, the larger the possibility of future predicaments such as this one. Scorponok on the other hand sees an unprepaired world ripe to conquer, though not as easy as ancient Earth theoretically been for them, he is still convince from what little opposition they have seen that this is just another world of inferior carbon life forms and for the first time in Predacon history they have popular support from a sufficient part of the population. Instead of taking more risks with more time travel missions to Earth, the liberated humans could be future infiltrators of the rogue planet, they may even be able to fool the Maximals for a little while, who do not seem to have any presence on this resource rich world.
Because his superior is not interested in anything but his original mission and his subordinates seem to blame him for the incident though Scoropok is going to need more than just reasoned proposals to win them over. He will need results. Intelligence from the indigenous population suggests one of "Moo's" top brass, Naga of the "big bad four" has been dispatched to supress the Predacon advance. Scorponok resolved to meet Naga's forces alone, informing only Inferno of his plans. It was invevitable that the loyal ant would eventually tell the queen of what was transpiring but it would be more than enough time to dispatch the conceeded flesh creatures. It should resonate strongly when one of Predacon singlehandedly fells Moo's, they will naturally displace this sacred cow "Moo" as deity in the simple minds of the carbon creatures and then perhaps Megatron will be more strongly convinced of this planet's great worth and resolve to see the fight for it through to the end.