I understand what you're saying, it does feel ruthless but what did she think might happen? I looked into the thread and it seems she sent samples to a Tesco product developer trying to expand her sales without protecting her intellectual property (apparently because plasters are already patented or whatever and you can't patent colours). She took a risk. It's business.
The publicity will probably get her selling more plasters than she was before as people seem to be on her side but she can't claim that a) she invented flesh toned plasters in a variety of shades or b) that this is surprising from a huge retailer when she left herself open.
What is now more likely is that some other big retailer will see this as good publicity for them and stock her brand. This would be no less profit driven.
Also i don't understand the point the Twitter makes repeatedly about Tesco not paying black influencers to sell the plasters. Why should they necessarily? They are a household name and have their own means of advertising.