A wild guess would be the selectors looked at her 1500m and 800m times and decided they weren't world class, forgetting that the Steeplechase is quite a different event, and some athletes make their best races in championships, so without that opportunity, you will never find out how good they are. Also her mother isn't a former World 10,000m Champion married to a leading coach, so she isn't Olympic potential for being at the back of the field, like past selectees.
As for Vernon, the message seems to be the British selectors don't want improving white athlete championship performers who have opinions, so most other white British men should just give up. It doesn't matter how good you are, you won't get selected (unless they know your parents/coach).