Is the court saying that evidence of the expert who ascertained the views of the children is unchallengeable and the foundation of those views and any conclusions cannot be tested?

This appears to be an issue of procedural fairness.

How does the court know that the views are genuinely held and not subject to parental influence or dictation.

The court perhaps should have afforded natural justice advising the applicant that if the application is held to be without merit that costs under s117 would likely be ordered.