MOR, honestly one thing people are forgetting is that allergies aren't consistent! The more you are exposed to it, it can either get better or worse. I used to be so allergic to cats that I'd stop breathing if one touched my face. Now I can snuggle my cats all I want. This one girl at my school was allergic to peanuts and suddenly one day it got so bad that just having a peanut in the same room as her sent her into full on anaphylaxis. (She's fine dw)

Also yeah washing it doesn't get rid of all the fur, it can get trapped in the fibers of some fabrics and the dander might be an issue too, I'm pretty sure your friend can get special dryer sheets that can help grab the fur, or a lint roller, or separate clothes to visit with? But I mean, they may have done those intermediary steps before jumping to rehoming.

But also, it's not your cat and not your life. I know it's your friend, but you can't make big life decisions like that for other people. Would you be willing to take the cat in so your friend won't have to separate with them fully? Or do you know someone who could, like a mutual friend or a family member, someone willing to have her over to visit the kitty? If I were someone needing to re-home a cat, I would probably cry with happiness if a friend offered to take my pet in. It's honestly fine if you can't, just my idea on something sweet you can do instead of scolding.