A visit, or even attempted visit, from the world's most prominent religious leader would be a profound statement against the politically motivated imprisonment of Alexei Navalny.

I, the author, am not a Catholic nor have I ever been very good at practicing any particular religion. But I am a devout HUMANIST, and that has always functioned well enough as a guide to stand for fundamental human rights & oppose institutionalized abuses. 

A visit from the head of the Catholic Church is a statement of care, personally for Mr. Navalny, and care for the prisoners of conscience throughout the world.