Rubio is a soft Republican, but still ultimately a Republican.

Also people need to remember - Those who voted to certify the election didn't necessarily believe the election was legit, they didn't believe they were in a position to fix it. Rand Paul comes to mind.

If on principle they don't think Congress can reverse the election then they wouldn't vote against it.

In a manner of speaking they are correct. It is the State Legislatures that ultimately should have done something and perhaps they still might.