I don't find much fault with snake in 2. he got conned at the tanker(just like solidus) and his mission after that point was to figure out what was going down. when he got to the source and came out the other side he came to the right conclusions, solidus was a regrettable side obstacle and the patriots were the real threat they'd need to pivot their crusade towards. I think the original concept for 4(pic related) was going to follow that line, more overt war with the patriots angle.

however for whatever reason kojima decided to have snake slide back completely into being a pawn and repeat the mgs1 liquid 'sunglasses' bit.