He was consistently keeping up his side of friendship for Arthi until this task without any actual benefit from her.
We all know it's pointless to save sana cos after getting saved she will do another flip.
He finally gave respect to the paras support.
It's a totally different debate as to why paras supported siddharth it was not real friend ship and even siddharth realises paras end of the friendship n accompaniment was for the game. But that's what siddharth liked about the nalla useless paras is his loyalty towards him which did not budge after the first flip he did post rashmis eviction.
Ps : I prefer paras being saved over freeloaders Arthi n mahira.
I just hope juzzbaathon mein behak kar kahin sid mahira ko bhi save naa kardhe