I don't believe this was the point I was addressing in response to the grandparent. If two candidates appear where one has a much better skillset, it makes sense (in most frames) to accept the better candidate, I agree.
What I was responding to was how there may be no responsibility for the American to renounce his privilege such that the Syrian has an easier time becoming a possible candidate (Both in skill set as well as logistically). Additionally, it may even be irrational for the American to do so if we consider them as adversarial actors (In competition, unlike when recruiting co-workers).
Please understand my commentary here is simply in response to the equally extreme logic applied by the grandparent (A world of no nations/borders being optimal) and by no means constitutes my complete opinions on immigration, visas, and the like. We can hopefully elevate the discussion above, allowing immigrants only out of charity, to more rigorous reasons.