Is this how humans write diaries? It sounds very artificial, like the narration at the start of some movies or the scenes where to inform the viewer, characters tell each other things that, in context, they would already know.
I suspect that this is not genuine and that it is intended to sound heroic (by North Korean standards). Maybe it’s North Korean propaganda or maybe it’s something this guy actually wrote, but as a display of his loyalty rather than as a record of his thoughts. (I expect that he would know better than to write down anything other than a display of loyalty.)
I don’t think Trump reacts well to being disrespected, whereas a more normal politician wouldn’t make major decisions based on personal feelings. I suppose we’ll see what the Russians say to Trump’s face, but if this is going to be their attitude then his response might be dramatic (especially since Zelenskyy is sure to flatter him).