Sympathy is often used as a trump card for many contestants. Hence, outrageous comments are given by judges to save contestants whom they think are worthy.
Case 1: Anu said Emon was overconfident. It brought back Emon in the limelight (when he was fading away from public notice) and made the public furious for "unjust comments"
Case 2: Javed says Emon is not fit to be a playback singer and makes silly excuses about his voice not fitting with an orchestra (Come on! there are even thinner voices out there!). Public is outraged from what you can see on this forum alone.
This is meant to create sympathy for Emon so that he does not get eliminated. Has been done before in other shows too.