Cheney, one of the most conservative voices in the House, is going to "do and say" what the Democrats on the Committee tell her to "do and say?"
Look at the history of this Committee, right after the attack both McCarthy and McConnell called for an investigation into the events of the day. Pelosi gave McCarthy and McConnell everything they asked for, everything they laid out they wanted, even the power for the Republicans on the Committee without a majority vote to subpoena anyone they wanted. At that point, both Kevin and Mitch said they weren't interested, in other words, they didn't want any investigation, largely for political reasons
So Pelosi went ahead and started a Committee, and when requesting McCarthy's recommendations for members, Kevin sought to purposely sabotage the Committee by appointing two Representative famous for their theatrics. Pelosi didn't accept them, McCarthy pulled the plug, and the other two GOP representative felt the matter did need attention and stepped forward
To dismiss the Committee as totally partisan is inane, right wing deflection, and the Committee's purpose is to determine who "broke laws" and should be "held accountable"