Well, but does s/he REALLY know genetics? Who are the male and female? We haven't been told that, have we? S/he knows colors, to a point. Yes. But a lot of non-breeders do, too. I'm no good with genetics, but many people study them and don't plan on breeding.
Most of the rat fanciers ARE weary of anyone breeding, as with most groups of pets out there. Mainly because there are SO many unwanted rats as it is. There is SO much inbreeding, accidental breeding, feeder breeding and backyard breeding that we DON'T really think there's a need for more rats coming from bad lineage. So many are unwanted, and I can tell you that for a fact. We have 25 rats (and a mouse) here at Rattie Love Rescue (we try not to go over 20). So many other rescues have SO many more (one in MI has 70-some, there's another in CA that has over 300, etc). Each rat born and adopted out means one less rescue rat has a home. It's a huge issue, and many of us ARE upset about yet more rats being brought into the world, so we tend to question people who are breeding. If they are going to put more rats into the world, then they SHOULD be high standard, from a long line of established lines. Most "breeders" don't bother and don't care.
I am NOT anti-breeder. I mentioned above that there's already an established breeder in Pinellas. She's a very good friend of mine, actually. Another of my good rat-friends is a breeder. Again, established, mentors under a very well known breeder, etc. Really, as I feel all breeders should be. The standard SHOULD be high for adding more problems to an overpopulation.
Of course it's his choice. But we have a right to stand up for what we believe in. This is a public forum, we are all entitled to our opinions and as long as we are polite about it, speaking them.
With a price like $5, though (if it's not a typo), there WILL be people who will want to adopt and use them as feeders. Well known fact, here. Also, people scouring for animals for labs that will take whatever they can get... $5 isn't a bad price since the people get paid for dumping the animals. A good breeder KNOWS these things and not only that, would not want to let rats of good breeding go for so little. It's a warning sign if a breeder would adopt out rats for so little money. Says a lot about what they must feel about the quality of their rats.
Also, very well-educated breeders SHOULD be able to know what they're getting, because they should either own the lines or have gotten them from other breeders who know the lines. There may be the occasional rarity or whatnot, but breeders should be able to say that this litter should have mostly this, that and the other thing. If they can't, we question if they really know the genetics, or if the mating pair are pet store rats, etc.
Why shouldn't we question it? As I said, people are bringing rats into a world that is already full of unwanted rats. Every breeder rat that's adopted takes the place of a rescue already looking for a home. Rescue rats die because someone decided to go with a "breeder" rat, even though sometimes, they're parents are pet store rats with someone who thought it'd be nice to have cute babies or whatever.
I'm not saying this IS the case here. I hope not. But as far as we know, this person is saying $5 for adoptions, hasn't listed the parents, hasn't mentored under an established breeder we assume, etc. These are things that separate the established ethical breeders from the feeder breeders or the backyard breeders.