Asim's sudden skyrocketing popularity. They thought if they start treating him like Rohan from BB10, they'd be able to chuck him outta the show but their plan backfired against them cause Rohan's fansupport wasn't as big as is Asim's. They must be cursing themselves for not evicting him early on, cuz he only destroyed their plan to have their fixed top 2 SidNaaz & he's becoming the obstacle in their fixed winner Shukla's path as well to win the trophy!
Like they evicted two of the biggest threats at early stage Koena & Daljiet. They can't evict him now like they wronged Nehha Pendse last year who surpassed BB's fixed top 2 Bhai-Behen jodi in fansupport with minimal screentime, got her out when she was about to start playing her game, cuz they didn't want to take risk of viewers extreme outrage in the long-run. That still remains the most unfair eviction ever of BB history!