Creationism is testable...
You can test whether the universe is older than 6,000 years... turns out, it is
You can test whether god could create light before creating the sun and stars... or creating plants before the sun (bad idea; god didn't really think this creation plan through)
We have artifacts from civilizations older than 6,000 years!
We have artifacts from Egypt dating across the entire period where a "global flood" is claimed to have killed everyone (i.e. the flood didn't happen either)
We have fossils that are millions of years old!
You can test many aspects of the creation hypothesis, and it fails every test
I disagree that creationism is testable, though I do agree with everything else you say. Perhaps it is splitting hairs but since we are trying to be precise in our language I would argue that yes the *arguments* that creationists often use some are testable but the actual one and only hypothesis of creationism, that God created everything, is absolutely untestable. We can debunk every strawman or logical fallacy that creationists throw up but they will just move the bar, because it's not reasoned discovery of the truth that they are interested in, it's confirmation of already held beliefs only. Their arguments are shields, not real scientific discourse. That's the point, creationism is in no way shape or form science.