"Committee for Privileges
The Committee is chaired by the Chairman of Committees and is made up of fifteen peers, including four Lords of Appeal."
The Committee hears complaints of prima facie breach of privilege, takes evidence, and reports its recommendations to the Lords, where they are debated before the House decides whether or not to accept them."
What Sivakumar did was legally wrong by not referring the Committee's recommendation back to the State Assembly to be debated and thereafter a vote to be taken.
The provisions of the Standing Orders can be read in my earlier posting here