If they can survive for an extended time without a heart, then they can "survive", but it doesn't mean that "I have a few minutes before the loss of oxygen kills me", as it's a curse.
And again, the heart teleport only works if BB's shenanigans are made irrelevant. You need to first explain why Fragarach didn't kill stein from the start, second explain why he could somehow get the heart, and third explain how he got around the Voyager's Yukari-Barrier.
And again, the heart teleport only works if BB's shenanigans are made irrelevant. You need to first explain why Fragarach didn't kill stein from the start, second explain why he could somehow get the heart, and third explain how he got around the Voyager's Yukari-Barrier.