Filtering with whitespace regex not working

I have nominal attributes Entity and EntityType. Entity contains a number of names of people and organizations. EntityType contains which type the Entity is (Organization or Person). I am trying to filter on EntityType == Person where Entity contains a full name. I want to omit single names.

I am using Filter Examples with attribute_value_filter. The string parameter is set as below.

EntityType = PERSON && Entity = [a-zA-Z]*\s.*

This does not select any of the names. I think I have isolated the issue to the whitespace character class within Entity. Any filtering on whitespace fails. For example, all of the below parameters failed to catch Bart Simpson.

Entity = Bart\sSimpson

Entity = Bart[ ]Simpson

Entity = Bart Simpson

However, the below worked.

Entity = Bart.+Simpson

Any ideas on how to match full names?

Below is an example of how I want my filter to work.

Input
Entity              EntityType
Fox Network         ORGANIZATION
Homer J. Simpson    PERSON
Homer               PERSON
Marge               PERSON
Bart Simpson        PERSON
Lisa Simpson        PERSON

Desired Output
Entity              EntityType
Homer J. Simpson    PERSON
Bart Simpson        PERSON
Lisa Simpson        PERSON