The man was running for POTUS. Do you expect the men who lead the world to uphold your own moral standard?
From Machiavelli's The Prince:
>Every one admits how praiseworthy it is in a prince to keep faith, and to live with integrity and not with craft . Nevertheless our experience has been that those princes who have done great things have held good faith of little account, and have known how to circumvent the intellect of men by craft, and in the end have overcome those who have relied on their word. [...] A wise lord cannot, nor ought he to, keep faith when such observance may be turned against him, and when the reasons that caused him to pledge it exist no longer.
https://en.wikisource.org/wiki/The_Prince_(Marriott)/Chapter...