Having learned more it appears the initial use of "Mr" on the phone call was an understandable error.
At this point the staff were all aware that this sick person was from a sex offender wing of a prison, that he was large, that he was shackled to two prison officers whose responsibility it presumably was to keep the staff and the other patients safe.
By the point of the phone error the trans person was apparently already angry, dysregulated, and upsetting other patients.
I don't think it was Jennifer's fault that he behaved like that either before or after her interaction with him; he is responsible for his own intolerable behaviour.
I do think it, however, wasn't the right or judicious moment to double down on the accidental use of the term "Mr" and justify it, to someone who was never going to deal with that well, even if not ill and not already dysregulated. I think it was predictable that an outburst of some sort would follow. That does not make it right or acceptable or excusable.
To what extent a lead professional in a situation should work to de-escalate moments of tension that could be dangerous in their work environment appears to be one that most people have differing views from me on. I would say de-escalate first, be right later.