That's a big stretch of a headline based on what they're quoting. Trump was certainly being his inflammatory asshole self, and seemed to opine on what he thought the Lt Gov should or shouldn't do. I didn't read his words in an intimidating way at all though.
It came off more as a brash "he shouldn't testify because he doesn't know what he's talking about" as opposed to "he shouldn't or else bad things might happen".
The headline literally says “told him not to testify”, not “threatens him to not testify”? Not sure what you’re referring to? What “stretch” are you pointing at?