I think so, if we recognized it as machinery there must be some features that would lead us to suspect this, features that align well enough with how we view technology for us to see similarities. I think the abduction inference would be intelligence. I don't know how we rule out other humans, some secret program or another but if you want to state that in this thought experiment that no humans were nor could possibly have been there I think alien intelligence is more probable than a natural process.
And you are able to come to this conclusion without knowing anything whatsoever about this intelligence. You know nothing about where they are from, who they are, what they look like, how old they are, what they are, where they are now, etc. etc.
You can explain none of these things. They are a mystery to you and yet you still can rationally infer that this intelligence, whatever and whoever it may be, is the reason or cause for the machinery being in that cave on Mars.
This thought experiment highlights that philosophers of science, in recognizing a hypothesis as a good hypothesis, don't have to have an explanation of the hypothesis in order recognize it as the best hypothesis.
So the conclusion of the Kalam cannot be objected to on the grounds that we don't understand how the cause could create the universe, or what this cause is like, or the fact that the cause is mysterious to us. We don't have to be able to explain these things in order to recognize that the hypothesis that a spaceless, timeless, immaterial, immensely powerful, personal agent caused the universe to come into being, is the best hypothesis. All of these things may be mysterious and beyond our power to comprehend and explain just like the whereabouts of the intelligence responsible for the machine parts on Mars.
Yet in both cases, this does not prevent us from rationally concluding that an intelligence is the cause.