Tbh I feel like the government in Kyiv is pretty much the only thing preventing Ukraine from collapsing as it is. Ukraine with the 'capital' of Lviv would be the beginning of the end because it'd leave Russians free access to the actual capital which would be a MAJOR conquest in the war, plus moving the government out of Kiev would naturally require a decent amount of troops to accompany them (splitting everything up and creating easier to defeat armies), otherwise you're just completely leaving Lviv open for the taking after Kiev falls. Turtling within Kiev is a stupid move but basically means that Russia has to commit some really hideous attacks in order to take Kiev and it's in Russia's best interests to capture Ukraine as 'cleanly' as possible so a future government can run things with minimal turnaround.
Under no circumstance does Russia want to accidentally shell Zelensky, their perfect 'win' requires either Zelensky surrendering or being captured alive and given a 'fair' trial.
It's actually a solid plan by Zelensky if it works, he's basically baiting Russia into committing horrific war crimes if they want to take Ukraine. It's stupid, suicidal, and puts regular Ukrainians more at risk of getting killed but it creates a stalemate that might last long enough for the Ukrainians to beg Zelensky to surrender, making him look like a hero who begrugingly accepted whatever it takes to stop the bloodshed.