This is the counter argument but I find it deficient for several reasons. We don’t’ understand exactly what gravity is but we can create a predictive model of how it works as its function can be empirically demonstrated.
We don’t know exactly how a human mind or Divine mind works but we know by experience that it is capable of conceptualizing how to process and analyze information and conceptualizing how to arrange parts for a function that we can assign a reason. Overall it is able to generate complex concepts on its own.
The objection that we cannot hypothesize that a mind is a mechanistic explanation for an observation just because we cannot observe its direct action does not have a scientific precedent. I therefor think this objection is arbitrary and simply trying to make the hypothesis go away.
Also, having a mind as a mechanistic explanation is very useful for science as it provides a strong counter argument to help with rigor for evaluating a hypothesis. I think exploring the possibility of a multiple origin hypothesis is an exciting project for evolutionary biology and would make positive use of all the gene data that is currently being generated.
Without this we are simply repeating the assertion of the LUCA hypothesis without rigorous empirical support beyond comparing it to separate origins without design (random change plus cellular mechanisms) and asserting that a partial nested hierarchy is only explained by the LUCA hypothesis.