Ulmer, in his very first book, immediately distanced himself from McLuhan because he felt like McLuhan was privileging / encouraging a return to orality. The point you are making about Ulmer distancing himself from Ong is pointing out the same kind of positioning move--Ong was McLuhan's student, and both Ong and McLuhan are more conservative than Ulmer, and part of that conservatism is manifest in a certain nostalgia for oral cultures. Ong and McLuhan have more faith in the immediacy of the oral word (to bring Bolter and Grusin in) than does Ulmer, and Ulmer does not want to see the "literacy" of the 21st century return to an easy acceptance of immediacy and transparency.
That paragraph might have more background information than you need. What's relevant for our unit and our course, however, is understanding that Ulmer is trying to help us think about a new kind of literacy that is not fundamentally "oral." The MyStory, as you hint, shouldn't just be a "familiar telling of a tale," it shouldn't be just another story about the clear and easy coherence of your identify. Instead, it should be a story of the ways in which you perhaps have to force or yoke "discourses" (career, family, entertainment, community) together to find a coherence that you probably will acknowledge is accidental, social, and fragile, rather than natural, unique, and solid.