IMO BB thrives on rivalry between 2 HMs and it's evident that BB wanted a Sid vs Rashmi a la Shilpa vs Vikas mode, but that didn't take off the way BB wanted.
Also BB wanted a Sid vs someone rivalry. Paras was never interested as he tends to play safe and from behind. Sid was constantly getting into fights with females and looking aggressive and bad. Though again in that, it was never about only Sid being wrong, coz it was clear that the females were provoking Sid and Sid was reacting violently. BB must have realised they couldn't continue with this as someday Sid might lose it and literally get physical with the girls.
When Asim and Sid fought, BB got their man in Asim to go against Sid as man vs man doesn't look as bad and Asim is not the one to play victim and that is why Asim was praised during wkw, when all females have been slammed for going against Shukla.