I mean Fedorov thinks so, I imagine you would have to suspend martial law. Zelensky didn't say it's unlawful just that it would "destroy Ukraine".
I imagine it would quickly devolve into the question on whether "Ukraine should continue fighting until it wins the war" (24% in 2024) or "Ukraine should seek to negotiate an ending to the war as soon as possible" (69% in 2024). Obviously opinion could have changed quite a bit since then. And Fedorov doesn't seem to be the peace negotiation type either.
Should Ukrainians get a vote on that or not? If democracy is not for deciding such monumental questions, what is democracy for? Just saying "oh that's unlawful for Ukrainians to vote" is I think a bit... different.
Not that I think the terms Russia might dangle for a peace agreement would make for a good election platform lol. They want Ukraine to be neutral, reduce it's army, and want to keep the territory they conquered. And would probably also not agree to a ceasefire because they believe it would give Ukraine the opportunity to regroup.