The event happened in October 2017. Putin presented a new arsenal of nuclear weapons in March 2018. Some kind of indirect relationship is not impossible.
Their nuclear rocket is a development effort, not an operational weapon, and they haven’t claimed to have achieved the central technical goal of making a reactor small enough to put in a missile.
It's certainly a work in progress but it seems that they have been testing at least marginally functional versions of the missile complete with nuclear powered propulsion[1].
