Well, if the families are OK with it, I am too. Being the the architectural field, I dug a little deeper. If you look at the site plan for the design, it doesn't really look much like the "crescent" of the ROP flavor to me.
http://www.flight93memorialproject.org/docs/F93%20Board%2030x40%204-5.pdf
But, I can see where the name wasn't really thought through. I can tell you from experience that a LOT of changes will be made to this design before it ever opens. We have had whole projects change completely from concept to build. I would venture to say this will be no different.
There is also a PowerPoint Presentation about the site plan:
http://www.flight93memorialproject.org/powerpoint/FLT93PMAFINAL compress.pps
[Warning --- it's quite large at seven megabytes and their server seems to be quite slow.]