Abstract Appeal has an excellent detailed explication ofr the points of law and medicine that people ought to read. Some specific points — not offered as argument, but as a tease to get you to read the whole thing:

An assertion that the ward made a particular statement may certainly be challenged as unreliable — that the ward never said it — but there is no question that evidence of the ward’s oral statements is admissible evidence, or that oral statements may constitute clear and convincing evidence.

On the topic of whether the “de novo review” was properly done:

De novo review is a common type of review in which the lower court’s decision is reexamined in its entirety. No deference is paid to the lower court’s conclusion, and the appellate court decides for itself whether it reaches the same conclusion the lower court reached. Importantly, though, in a de novo review, the appellate court looks only to the record produced below to make its decision. The appellate court does not accept new evidence. The court can review transcripts, exhibits, and whatever else was before the lower court.

Not accepting new evidence is what distinguishes de novo review from a de novo trial.