If I understand it right after the first year the starting player card cannot be put back for 2 victory points...
I think you understand it wrong. The starting player gets his "starting player" character card while all other players get one as well at the beginning of the game. There is no reason why the starting player would need to be penalized with inability to sell the card while everyone can sell theirs. So, I'm pretty sure you can give up your starting player for 2 VP and retain the starting player status until someone else claims it.
so if I understand what you are saying even if the start player character card is amoung the available characters for whatever reason, given up, assassinated, etc, whoever had the character last retains the right to first worker placement in the game until the character card is claimed again.