8. If an investor is completely unwilling to sell a non-investible asset (say a property), should it be omitted?

We would not recommend this.

The Risk Capacity tool accounts for some unwillingness to sell by reducing the value of an asset in the Risk Capacity calculation, but not complete unwillingness.

This is, we feel, realistic. However much someone's stated unwillingness to part with an asset with which they have a strong emotional connection, there will always be circumstances where that changes.

These tensions are a valuable part of the investment discussion, and an acknowledgement that humans (and their goals) are more changeable over time than they are often believed to be.