Complex sentence: Portable Ops that he was invited to form the original Patriots, but it is not known if he accepted; however, since Ocelot implies that he is an important part of the plan, it is probable that he did.
Split into simpler sentences: Portable Ops that he was invited to form the original Patriots, but it is not known if he accepted. However, since Ocelot implies that he is an important part of the plan, it is probable that he did.