It's interesting watching the creationists wriggle. Their arguments have had to change (evolve) over time as discoveries in science made it impossible to support them. The age of the earth is one such seismic change but here we have another.
Until Darwin came along the predominent Christian belief was the fixity of species; they were said to be immutable, they could not change. They were put here by God as we see them now. Praise be! That idea had to change because we discovered more and more species and they all had to fit onto that mythological boat. Darwin came along just in time showing that species did actually change and now immutability of species has been totally abandoned by believers. It's even called unbiblical these days, despite being a firm Christian belief for centuries.
But by allowing species to change they opened the gate to evolution. So now the great wriggle is to stop evolution at a convenient point - they have to allow change, but not so much change that it can harms creation itself. Hence 'kinds' - an undefinable idea allowing as much or as little change as is necessary for any particular organism just so long as they can be on that boat.
This is tricky. The reason that CRR is being so pedantic about definitional issues of the ToE that no-one in science cares too much about is because he absolutely must find a definition which removes the logical conclusion of common descent. His job here is not to define the Theory of Evolution but to define OUT of the ToE common descent. He now needs to stop evolution at some convenient point for his beliefs to continue make some sort of sense to him despite the accumulation of evidence that they don't and they can't.
Science has forced a change in how believers believe since the enlightenment. Prior to that, the priest stood at the front and told their congregation what to believe and they believed it. Now individuals have to reconcile facts discovered about our world with folk tales and the folk tales can't stand up to it. In American fundamentalism I think we're seeing Christianity's final struggle against rationality.
Je suis Charlie. Je suis Ahmed. Je suis Juif. Je suis Parisien. I am Mancunian. I am Brum. I am London.
"Life, don't talk to me about life" - Marvin the Paranoid Android
"Science adjusts it's views based on what's observed.
Faith is the denial of observation so that Belief can be preserved."
- Tim Minchin, in his beat poem, Storm.