When the latecomer stands up to complete his prayer, he is praying alone, so he should not let anyone pass in front of him
Question

                It is known that the imam’s sutrah (screen) is sufficient for the worshippers behind him. But if the imam completes the prayer and ends it, will his sutrah still be sufficient for the latecomers, or they have to have new sutra? I noticed that some latecomers do not stop others from passing before them. So what is the ruling on this matter?.
Praise be to Allah.
    When the imam says the salaam and the latecomer stands up to 
    make up what he missed of the prayer, then at this point he is in fact 
    praying alone, and he should prevent anyone who wants to pass in front of 
    him, because the Prophet  (peace and blessings of Allaah be upon him) 
    enjoined that. If some people do not prevent people from passing in front of 
    them, it may be because they are unaware of the ruling, or because of a 
    different interpretation, because they think that since they caught up with 
    the congregation, after they start to pray separately from the imam they 
    still come under the same ruling as those who are behind the imam. But it is 
    essential for the latecomer to prevent the one who wants to pass in front of 
    him, when he stands up to make up what he has missed. End quote. 

    Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on 
    him).