There are several possible answers to that.
First, I did not claim to be able to explain the sensation of purple to a blind person. I said I can make that blind person understand that there is a property that is being consistently described by those claiming to see.
So, for example, I can have a variety of objects. the blind person could verify some of their characteristics by touch. Then sighted people can come in, one-by-one and describe that object. That they give consistent descriptions independently of each other would be evidence for the blind person that the colors mentioned are actual properties that sighted people can detect and the blind person not.
Alternatively, a blind person could use a prism to separate out the different wavelengths of light and verify that a certain range of wavelengths is consistently described as 'purple' by people who are sighted. This can be done in a way very similar to how we can detect and verify the properties of infrared light. We can verify, for example, that bees see some ultraviolet and the range of frequencies of light they can see even if we cannot see them ourselves.
Once again, my claim is that I can convince a blind person that there is an actual property that sighted people detect, since they *do so in a consistent way*. At no point do they actually have to experience color themselves to know that it exists and what its properties are.
Thank you for elaborating.
Then you are in agreement that unless one experiences the color purple for themselves, the experience is subject to someone else's perspective and/or experience.