[racist drivel]
You have no idea how recessive and dominant genes work, nor how they are passed on between generations. Go play with some Punnett squares
What is there to explain or argue? This is no different than asking a civil engineer to engage in a serious discussion with a "9/11 truther", or an aerospace expert to convince someone who's convinced the moon landings were faked. It's waste of time, because the opposing party is clearly unwilling to spend any amount of time and effort to learn the basic concepts of the respective field, and will solely aim to win the argument by rhetorical smoke and mirror tactics, not scientifically adequate reasoning.
In principle, you are right. But this "discussion" started by an abuse of rigidly defined terminology of the field that has currently the best understanding of the topic in question ("recessive", and "biology").
If someone claims that prime numbers are divisible by some other number (other than 1), do I need to seriously argue against that? There's obviously a difference wrt absolute certainty between a purely formal result (of pure math) and an empirical result (like in biology), but even in the latter case, the result is still a lot closer to "certainty" than to "totally up for uneducated debate".