Are expired certificates ever rendered invalid as well?

Question

Links

Navigation: The Fathom Protocol > Architecture Overview > Concept > Expiration Time

Excerpt from white paper:

Members who have been assessed in a concept longer ago than specified by the expiration time do not lose their certificates, but can no longer take part in the process of assessing others.

Thoughts behind the question

Shouldn't there be occasions when a given certificate is both expired and invalid?

For example, a drivers license is issued with an expiration date. Once expired, it loses its validity. Not only are you unable to legally drive a vehicle with an expired license, you are also unable to use an expired license as a valid form of identification. So the expired license ceases to be of value, except as a souvenir.

An individual may never lose a certificate even if it's expired (as the individual's attainment of that certificate is forever recorded to the blockchain). However, in addition to being disqualified from acting as an assessor, shouldn't there be mention of a loss of utility (however utility is defined by its concept/community)?

Suggestions

Our existing documentation doesn't contradict the idea introduced here. However, I think it's worth adding some mention of this distinction into the white paper.