I think blaming the Kansas SoS here is wrong. If the KS election law explicitely says that you can only step down as candidate by notifying the SoS that you are unable to serve if elected, then Krobach is only acting according to the law. It's his job.
You should rather expect the Taylor campaign to be smart enough to know the election law and they should have put the "unable to serve" thing into his letter.
Except the letter Taylor wrote was written with the assistance of the Secretary of State's office, implying the Secretary of State knowingly deceived the Taylor campaign.
Its much more likely that they consulted some mid-level bureaucrat in the office who got it wrong. I very much doubt the secretary himself was involved in the decision in any way.