I am hardly "anti-evolution". IF anything resembling intelligent design played a part in the beginning or subsequent development of life on Earth, IMO most of the process was clearly left to evolution. I don't see intelligent design as excluding evolution (though certainly many of the loud ID proponents are promoting a version which excludes most aspects of evolution).
In the hypothetical scenario I gave, of contemporary scientists deliberately producing one or a few simple one-celled organisms which could survive and evolve on Mars, that would be "intelligent design". And if no human or other intelligent entity ever touched or influenced Mars again, a few billion years down the road, some highly evolved intelligent Martian creatures would be correct in hypothesizing that "intelligent design" had played a role in their coming into existence. That would in no way negate the fact that they had evolved from simple one-celled organisms.
Neither do I. Neither do all (or virtually all, there may be an exception or two) of the pro-E posters on these threads. What is objected to, fundamentally, is that anti-Es think ID should be taught as a scientific theory when it is not. Another big, but lesser issue is that anti-Es pretend that evolutionary theory isn't scientific when it is, in fact, a very strong scientific theory. In most cases I'd say this is simply abysmal ignorance of evolution and science in general. For example, I wish I had a dime for every "if humans evolved from apes, why are there still apes?" post. But there are a handul for whom science and its naturalistic methods are an affront for religious or philosophical reasons.
As for your hypothetical scenario, a highly evolved Martian descended from primitive, designed creatures could propose that their progenitors were designed, but unless they could make testable predictions from that proposal, it would be "true" but not scientific.