Additionally he’s only treating the common use of “creationism” and “creationist” as isolated nouns, completely avoiding the fact that they are also commonly used in adjectival noun phrases, specifically with the broader meaning that he wants to avoid.
He’s also ignorant of how old terms such as “evolutionary creationism” and “creation by evolution” are, but that’s another story.
Yes. That’s precisely why terms such as “creation by evolution”, “evolutionary creationism”, “Young Earth Creationism”, and “Old Earth Creationism”, actually predate the term “intelligent design”. I have no problem at all identifying myself as a kind of creationist; specifically, an evolutionary creationist.
No. That’s precisely why “creationism” and “creationist” continue to be used in common terms such as “Young Earth Creationst” and “Old Earth Creationist” and “Evolutionary Creationist”, because people fully recognize that it is of use in identifying distinct parties in origins debates. No one reading those terms says “Well you’ve used the word “creationist” each time, so it’s totally unclear how they’re all different, they all look the same to me, I can’t tell them apart”.
The use of the word “creationist” in those terms does exactly what it’s supposed to do; identify what they all have in common. That’s precisely how it’s used when speaking of “ID Creationism”.