In the case of disagreement the only sensible option is to disable the MCAS and alert the pilots. Simply ignoring the secondary sensor is not a valid solution.
This is true. Which means per FAA certification standards MCAS should have been a "hazardous failure" system. Which means it should have had at least two levels of redundancy. Which means it should have never been certified with no redundancy at all for a failed sensor.
The handling characteristics change, but from what I understand it just tends to pull up. Any pilot should be able to deal with that as long as the artificial horizon is working and they are paying attention.
Plus, even if their attention does wander there are other safety systems (like stall alerts) that will kick in to help them.
It's not like the MCAS disengagement makes the plane uncontrollable.