Maybe Putin's colleagues found out something interesting about Trump back in the days, and made him an offer he could not refuse - "go and become King of America, we'll even help you a little, but you'll serve us".
Wild speculation, of course. But he definitely doesn't have national interest burdening his mind in any way or manner.
P.S. If I worked in the Secret Service, I would use my telescope to watch birds fly and tree leaves wobble. Even if there was a remote weapons station turning towards my client, or a wire guided object coming in - I would hardly notice until impact.
I guess eradicating a current fuhrer is Too Soon for sympathizers. It they have something to gain from a shit stain being in control for a bit before it circles the bowl enough times to finally disappear.