I personally believe cosmic ID (fine tuning argument) is a metaphysical stalemate pitted against theoretical physics models of an infinite number of universes. Cosmic ID convincingly demonstrates the physical constants in the universe lined up against almost impossible odds to allow carbon based life to exist. Multiverse models say there’s an infinite number of universes with different physical constants. Almost impossible odds can be beaten by an infinite number of trials. Neither theory can be advanced by experiment or further observation in my opinion.

Biological ID on the other hand is within the bounds of experimental biology to test against alternative theories. For example it’s quite possible, in principle, to construct a plausible detailed scenario wherein the flagella came about through nothing but random mutation and natural selection. As biochemistry, genetic engineering, and related fields advance it becomes possible to not just speculate about the evolutionary series of steps needed to build a flagella but to actually produce living creatures with flagella in each stage of the process. Conversely it might be found that a needed step is not reasonably possible to accomplish without intelligent direction.