As someone previously stated they should vote based on the rules set within their states for delegates. If that means some have released to other cantidate (aka Trump) then that is the way it goes.
Based on the way you’ve framed it (and I know unintended) that is a democracy of the majority vs a representative republic.
1. be entitled or appointed to act or speak for (someone), especially in an official capacity.
If your delegated representative strays from serving the appointing person or group of people, you are not being faithfully served. You are not being represented--they merely used your banner as cover for a personal agenda.