See, some of you seem to think that design by physical tools and methods is indistinguishable from design by a magic wand. This is not correct. If life was engineered by specific mechanisms (e.g., rational design of proteins), then we can plausibly detect hallmarks of this within genomes.
Well, wouldn't that depend on the waver of the wand, and whether s/he was into what you describe as "rational design of proteins"?
I can see no reason why someone using purely naturalistic methods would wish to create a LUCA clearly distinguishable from the LUCA that would be created by someone with magical powers. If two people have exactly the same end in mind, and one uses magic to achieve this end and the other doesn't, how would we distinguish between the two different means by looking at the two identical ends?
Your definition of creationism seems to be a bit idiosyncratic IMHO, and not one that will be found in dictionaries of the English-speaking world. Just sayin'.
But actually that is how the word "creationist" is used. No-one on either side uses it just to mean someone who believes in a Creator. Maybe that's what it should mean, but it doesn't. A creationist is one who denies evolution and asserts fiat creation of species, or "kinds", or whatever jargon they're using this week. And if you actually look at those "dictionaries of the English-speaking world", you will see that this is so.