This discussion is getting long and is certainly off topic as straddles are not allowed in tournament poker. That said, I will do what I can to answer your question.
A player who has chips in a cash game (since straddles are not allowed in a tournament) and who is absent from the table does NOT get dealt into the hand, does not post blinds, etc. Although blinds usually have to be made up if the player wants to return before it is his turn for the next Big Blind. It is just as though the seat does not exist. Therefore, the next player would, in theory, be able to restraddle. Now, it is necessary to look at the house rules to determine whether straddles are allowed and if so, the specifics applicable. In many, if not most, card rooms, the ONLY player that can straddle is the UTG player (1st player to the left of the Big Blind) and multiple straddles are not allowed.
Remember house rules prevail.
Now if you want to get really confused, I suggest you look up "Straddles in Poker" on Wikipedia. That description includes all kinds of different bets that are possible in cash games. None of which are allowed in tournament poker.