I was looking at Megatron's original alt mode finding it strikingly similar to the Nemesis. Which could indicate he patterned his alt mode alter it. Also if we go by the second pic the three prongs on the Nemesis could be armaments as well. Most Autobots and Decepticons though seems to prefer meteor forms for space travel. With exception of Megatron and Starscream who travel with whatever alt mode their with. Course given the aesthetics and Optimus' transition mode specifically shown it could just mean the smooth clean design he is benevolent while Megatron and the Nemesis being spiky jet and warship are malevolent. Ryan Church the concept designer pretty much did the same with Star Trek.