What made Amar look bad is not that he nominated Sharadda as if Sharadda was asked to nominate inside confession room with 2 others will mutual consent then she may nominate Amar too.
But first he not even tried to save her and ready to take her name from the very start and after doing it felt no sorry for her. In contrast, sid was firm to not take shonali's name. Even in previous nominations when Sid and Sky were given a chance to nominate 4 contestants then Sid tried till last to not to take Shonali's name and relented to sky's decision half heartedly.
Second after coming out when she asked that why he didn't stood for her he said I fought for you.. ye dekh, Ann (food) hai mere haath mein.. tum video dekh lena.. and then shamelessly said to sky that don't say to sharrada that I nominated her because when she'll be evicted then she have to take the name of one housemate for eviction and she can take my name.