I’m aware that the egg laying and meat breeds are generally different but the meat industry is bigger than just meat fit for human consumption. My family member owns a chicken farm, she sells eggs and sells egg laying and fancy breed chickens to people wanting to keep chickens and some of their older males and expired hens will be sold for meat, I presume for things like animal feed although admit I’m not 100% sure.
Sounds like she's very much at the small end of chicken farming, if she's selling purebreed chickens to the public? It's not a typical sort of farm that supplies the supermarkets by the sound of things.
Ex laying hens / breeding cockerels will be (a) tough and (b) if off an egg laying breed, scrawny. If they're being sold for meat, it'll be for soup, pet food and other similar low grade uses. You wouldn't roast one if you had any sense.
In terms of eating eggs from rescue hens, some of the vegans I know would argue that if the meat/ egg industry didn’t exist then there wouldn’t be a situation in which hens could be rescued, and that as such eating the eggs of them is still supporting an industry they disagree with. I think for many vegans (at least the ones I know) the underlying thought isn’t just that it is wrong to eat animal products because it is cruel but because using an animal for produce is ethically/ morally wrong.
I find this argument bizarre tbh.
The BHWT literally goes to egg farms on the day the hens are going to slaughter. They take as many as they have homes for, and the rest go to slaughter the same day. These hens will exist and will go to slaughter unless people rescue them.
Once rescued, there's literally no way to stop them laying - and at that point I take the view that the eggs should be used for something, though if the owner themselves doesn't want to eat them all they should be sold / given to friends, family and neighbours. Food waste is a major environmental issue, and there are far too many people going hungry in this country as it is.
Would they also say that rescuing a dog, via a charity, is supporting puppy farming if that dog was originally born in a puppy farm? Mind you I did once have a lodger whose vegan girlfriend told me that keeping pets was a form of slavery...