One can easily believe "X is good." without believing "X is what everyone should do in all situations." So to, one can believe "it would be better in numerous important ways if everyone did Z all the time." without believing "it would be better in all situations on all important measures if one more person did Z." You are advocating we judge others using a simplistic abstraction of what principles are. Good rhetoric perhaps, but not good thinking.

Put another way, it is untrue to think that principles can only be beliefs without conditionals.