I didn't see where she said she was planning to breed her rats. I don't think it's wrong to purchase/adopt a rat with a blaze simply because megacolon can run in the lines. I also don't think you can lay a blanket statement and say that nobody should be breeding blazes or other high whites. Megacolon doesn't automatically appear just because they're high white, it's just that they have a higher chance of it, and if you breed properly and research the lines you're working with, you can avoid it.