They shall in all cases, except treason, felony and breach of the peace, be privileged from arrest during their attendance at the session of their respective Houses, and in going to and returning from the same; and for any speech or debate in either House, they shall not be questioned in any other place.
1. It wasn't an arrest, it was a search pursuant to a judges (judicial branch, not executive) issued warrant in a (2) felony investigation.
Those pesky checks and balances.
And if they want to get in a snit over breaches of the constitution, they have had plenty of opportunity before now to howl about abuses. Screw 'em.