No......
Just imagine if the person is conceptually very sound with Six sigma methodology and there are no opportunity for him/her to do any project in the organization, or may be the management is not supporting, then it will be very difficult for him/her to prove potential skills.
Also, there is no guarantee that the project submitted by someone is really unique, and is not actually copied from some friend who has submitted the same project somewhere else. If the person has smartly copied, then the examiner would not be able to judge the authenticity of the project.
Even if you do Six Sigma project, no one can guarantee the successful completion of the project, but at the end of project there will be lot of learnings, which I believe will definitely help that person to do much better in future projects. Also, as we know that if our project is not successfully completed, our organization will not give any signoff.
Irrespective of the fact that person has submitted the project or not, interviewer will have to ask logical questions in order to validate his/her knowledge and skills.
Lastly, I would like to say that we should not compare the experience of Six Sigma projects with human operations done by experienced medical surgeons. Human life is always precious than any Six Sigma project because we cannot afford the loss of human lives.
Hence, I believe submission of project is not really important, but the sound knowledge is more important, and the basis of his/her knowledge one can definitely does a better job in terms of working on projects as well.