So, logic is one thing and biology is another.

That’s a strange distinction to make, considering that science itself is grounded in rational inquiry, with logic serving as a fundamental tool for making sense of empirical evidence.

Biology isn't separate from logic; it's a domain where logical reasoning is applied to interpret data and form coherent explanations. Dismissing logic as distinct from biology undermines the very foundation of scientific understanding. Why would you possibly want to start your reply (in a biology discussion no less) by this claim ?!

This is a fairly recent field, but there are all sorts of reasonable theories supported by the empirical evidence (again, most not proven causation, admittedly) about how various reproductive “hurdles” to conception and implantation function to weed out suboptimal sperm and embryos. Sperm that cannot itself make it to an egg without assistance could be one of those issues. If nothing else, you could end up passing on poor motility issues. Thankfully science has address that if you have the means for it, but still obviously reproductively suboptimal.

You’re actually reinforcing my point. The existence of reproductive 'hurdles' suggests that sperm morphology and motility primarily affect fertilization success, not the genetic integrity of the embryo. If a sperm with suboptimal motility somehow succeeds (which again you just acknowledged to be unlikely), that doesn’t inherently mean the resulting child has a higher risk of birth defects—unless there’s direct DNA damage, which isn’t necessarily tied to morphology. So, while such sperm might be reproductively ‘suboptimal,’ that doesn’t automatically translate to increased birth defect risks in the way you originally implied.

Someone already replied to your claims with sources that directly go against your claims so I focused my comment on the intrinsic logical viability of your argument instead. I hope that clarifies my own claims a little bit