My hunch is that most Western countries would be hesitant to allow anything that is nuclear + Russian on their shores. This article does not answer your question, but it sounds like as of 12/2020 the boat may be headed to the scrapyard due to needing costly repairs.
I doubt it has to do with it being of Russian origin - but more-or-less the unknown level of maintenance the ship and it's reactor have had since the fall of the USSR.
The reactors on these ships cannot be readily weaponized; there's practically no risk there. However, the reactors require a full crew to operate, even when just sitting in port being babysat (there is no "turning off" a rector).
During the collapse of the USSR, regular maintenance and full crew staffing would have likely been challenging, putting the condition of the reactor in uncertain territory.
https://www.strategypage.com/htmw/htseamo/articles/20201225....