The consumed star is no longer a gravitationally bound object, it is torn apart by tidal forces. She says the disk is supposedly unstable and half should disperse within hours and the rest within a month or so, so this delay is odd.
There is no way to return across the event horizon. You’d have to go faster than light and all timelines lead to the singularity inside the EH.
There is no such massive reservoir of unstable isotopes in stars and even if there was it wouldn’t all decay in a single event.