I learned, as an ESL student, that to use a colon, we need a complete thought. That’s, for example, what defends Mignon Fogarty from Quick and Dirty Tips (https://www.quickanddirtytips.com./education/grammar/colons.
I guess The York Times created a sentence fragment in their headline.
“My message to Hillary Clintos is:…”
What do you guys think? See a print attached.