So long story short, Malignant Mushroom is NOT in condition as of Christmas Day. Very chandelier and thin - looks like it completely collapsed not long ago.
Also worth noting, for those who have not already discovered this, is that Jojo's book does not describe its location/approach very well at all... his map shows it just slightly west of the park boundary - not the case! You can just see it from the parking area at the boundary - it is to the lookers Left and below the Phantom Crag rock climbing area. You do NOT need to walk up to the Phantom crag on the summer trail, its better to follow a different good hiking trail that starts a little further west from the riverbed.
All in all, a lovely day of driving and walking (and not much climbing) in a magical place. =)
Merry Christmas!
Jason Guptill ASG/ARG